* Re: [PATCH 1/3] virtio_pci: use put_device instead of kfree
From: weiping zhang @ 2017-12-12 13:11 UTC (permalink / raw)
To: Cornelia Huck; +Cc: virtualization, mst
In-Reply-To: <20171212110025.5d029fce.cohuck@redhat.com>
On Tue, Dec 12, 2017 at 11:00:25AM +0100, Cornelia Huck wrote:
> On Mon, 11 Dec 2017 23:55:16 +0800
> weiping zhang <zhangweiping@didichuxing.com> wrote:
>
> > don't free vp_dev until vp_dev->vdev.dev.release be called.
>
> Maybe add the same description as in your virtio_mmio patch so that it
> is clear why the kfree() is not ok?
OK, I'll add it at V2.
> >
> > Signed-off-by: weiping zhang <zhangweiping@didichuxing.com>
> > ---
> > drivers/virtio/virtio_pci_common.c | 17 +++++++++--------
> > 1 file changed, 9 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
> > index 1c4797e..91d20f7 100644
> > --- a/drivers/virtio/virtio_pci_common.c
> > +++ b/drivers/virtio/virtio_pci_common.c
> > @@ -551,16 +551,17 @@ static int virtio_pci_probe(struct pci_dev *pci_dev,
> > pci_set_master(pci_dev);
> >
> > rc = register_virtio_device(&vp_dev->vdev);
> > - if (rc)
> > - goto err_register;
> > + if (rc) {
> > + if (vp_dev->ioaddr)
> > + virtio_pci_legacy_remove(vp_dev);
> > + else
> > + virtio_pci_modern_remove(vp_dev);
> > + pci_disable_device(pci_dev);
> > + put_device(&vp_dev->vdev.dev);
> > + }
> >
> > - return 0;
> > + return rc;
> >
> > -err_register:
> > - if (vp_dev->ioaddr)
> > - virtio_pci_legacy_remove(vp_dev);
> > - else
> > - virtio_pci_modern_remove(vp_dev);
> > err_probe:
> > pci_disable_device(pci_dev);
> > err_enable_device:
>
> Otherwise, looks good.
>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Thanks a ton
^ permalink raw reply
* Re: [PATCH] virtio_mmio: fix devm cleanup
From: Cornelia Huck @ 2017-12-12 13:09 UTC (permalink / raw)
To: Mark Rutland
Cc: virtualization, weiping zhang, linux-kernel, Michael S . Tsirkin
In-Reply-To: <20171212125302.6846-1-mark.rutland@arm.com>
On Tue, 12 Dec 2017 12:53:02 +0000
Mark Rutland <mark.rutland@arm.com> wrote:
> Recent rework of the virtio_mmio probe path balanced a devm_ioremap()
> with an iounmap() rather than its devm variant. This ends up corrupting
> the devm datastructures, and results in the following boot failure on
> arm64 under QEMU 2.9.0:
>
> [ 3.450397] ------------[ cut here ]------------
> [ 3.453822] Trying to vfree() nonexistent vm area (00000000c05b4844)
> [ 3.460534] WARNING: CPU: 1 PID: 1 at mm/vmalloc.c:1525 __vunmap+0x1b8/0x220
> [ 3.475898] Kernel panic - not syncing: panic_on_warn set ...
> [ 3.475898]
> [ 3.493933] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.15.0-rc3 #1
> [ 3.513109] Hardware name: linux,dummy-virt (DT)
> [ 3.525382] Call trace:
> [ 3.531683] dump_backtrace+0x0/0x368
> [ 3.543921] show_stack+0x20/0x30
> [ 3.547767] dump_stack+0x108/0x164
> [ 3.559584] panic+0x25c/0x51c
> [ 3.569184] __warn+0x29c/0x31c
> [ 3.576023] report_bug+0x1d4/0x290
> [ 3.586069] bug_handler.part.2+0x40/0x100
> [ 3.597820] bug_handler+0x4c/0x88
> [ 3.608400] brk_handler+0x11c/0x218
> [ 3.613430] do_debug_exception+0xe8/0x318
> [ 3.627370] el1_dbg+0x18/0x78
> [ 3.634037] __vunmap+0x1b8/0x220
> [ 3.648747] vunmap+0x6c/0xc0
> [ 3.653864] __iounmap+0x44/0x58
> [ 3.659771] devm_ioremap_release+0x34/0x68
> [ 3.672983] release_nodes+0x404/0x880
> [ 3.683543] devres_release_all+0x6c/0xe8
> [ 3.695692] driver_probe_device+0x250/0x828
> [ 3.706187] __driver_attach+0x190/0x210
> [ 3.717645] bus_for_each_dev+0x14c/0x1f0
> [ 3.728633] driver_attach+0x48/0x78
> [ 3.740249] bus_add_driver+0x26c/0x5b8
> [ 3.752248] driver_register+0x16c/0x398
> [ 3.757211] __platform_driver_register+0xd8/0x128
> [ 3.770860] virtio_mmio_init+0x1c/0x24
> [ 3.782671] do_one_initcall+0xe0/0x398
> [ 3.791890] kernel_init_freeable+0x594/0x660
> [ 3.798514] kernel_init+0x18/0x190
> [ 3.810220] ret_from_fork+0x10/0x18
>
Oops.
> To fix this, we can simply rip out the explicit cleanup that the devm
> infrastructure will do for us when our probe function returns an error
> code. We only need to ensure that we call put_device() if a call to
> register_virtio_device() fails.
OK, that was the subtility I obviously missed. Reading through the
code, this seems correct (although I find the infrastructure a bit
unintuitive).
>
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Fixes: 7eb781b1bbb7136f ("virtio_mmio: add cleanup for virtio_mmio_probe")
> Cc: Cornelia Huck <cohuck@redhat.com>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: weiping zhang <zhangweiping@didichuxing.com>
> Cc: virtualization@lists.linux-foundation.org
> ---
> drivers/virtio/virtio_mmio.c | 36 +++++++++---------------------------
> 1 file changed, 9 insertions(+), 27 deletions(-)
>
> diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
> index a9192fe4f345..793b1085967f 100644
> --- a/drivers/virtio/virtio_mmio.c
> +++ b/drivers/virtio/virtio_mmio.c
> @@ -522,10 +522,8 @@ static int virtio_mmio_probe(struct platform_device *pdev)
> return -EBUSY;
>
> vm_dev = devm_kzalloc(&pdev->dev, sizeof(*vm_dev), GFP_KERNEL);
> - if (!vm_dev) {
> - rc = -ENOMEM;
> - goto free_mem;
> - }
> + if (!vm_dev)
> + return -ENOMEM;
>
> vm_dev->vdev.dev.parent = &pdev->dev;
> vm_dev->vdev.dev.release = virtio_mmio_release_dev;
> @@ -535,17 +533,14 @@ static int virtio_mmio_probe(struct platform_device *pdev)
> spin_lock_init(&vm_dev->lock);
>
> vm_dev->base = devm_ioremap(&pdev->dev, mem->start, resource_size(mem));
> - if (vm_dev->base == NULL) {
> - rc = -EFAULT;
> - goto free_vmdev;
> - }
> + if (vm_dev->base == NULL)
> + return -EFAULT;
>
> /* Check magic value */
> magic = readl(vm_dev->base + VIRTIO_MMIO_MAGIC_VALUE);
> if (magic != ('v' | 'i' << 8 | 'r' << 16 | 't' << 24)) {
> dev_warn(&pdev->dev, "Wrong magic value 0x%08lx!\n", magic);
> - rc = -ENODEV;
> - goto unmap;
> + return -ENODEV;
> }
>
> /* Check device version */
> @@ -553,8 +548,7 @@ static int virtio_mmio_probe(struct platform_device *pdev)
> if (vm_dev->version < 1 || vm_dev->version > 2) {
> dev_err(&pdev->dev, "Version %ld not supported!\n",
> vm_dev->version);
> - rc = -ENXIO;
> - goto unmap;
> + return -ENXIO;
> }
>
> vm_dev->vdev.id.device = readl(vm_dev->base + VIRTIO_MMIO_DEVICE_ID);
> @@ -563,8 +557,7 @@ static int virtio_mmio_probe(struct platform_device *pdev)
> * virtio-mmio device with an ID 0 is a (dummy) placeholder
> * with no function. End probing now with no error reported.
> */
> - rc = -ENODEV;
> - goto unmap;
> + return -ENODEV;
> }
> vm_dev->vdev.id.vendor = readl(vm_dev->base + VIRTIO_MMIO_VENDOR_ID);
>
> @@ -590,20 +583,9 @@ static int virtio_mmio_probe(struct platform_device *pdev)
> platform_set_drvdata(pdev, vm_dev);
>
> rc = register_virtio_device(&vm_dev->vdev);
> - if (rc) {
> - iounmap(vm_dev->base);
> - devm_release_mem_region(&pdev->dev, mem->start,
> - resource_size(mem));
> + if (rc)
> put_device(&vm_dev->vdev.dev);
> - }
> - return rc;
> -unmap:
> - iounmap(vm_dev->base);
> -free_mem:
> - devm_release_mem_region(&pdev->dev, mem->start,
> - resource_size(mem));
> -free_vmdev:
> - devm_kfree(&pdev->dev, vm_dev);
> +
> return rc;
> }
>
Shouldn't the cleanup in _remove() then be removed as well?
^ permalink raw reply
* Re: [PATCH v19 1/7] xbitmap: Introduce xbitmap
From: Philippe Ombredanne @ 2017-12-12 12:53 UTC (permalink / raw)
To: Wei Wang, mawilcox
Cc: yang.zhang.wz, kvm, mst, penguin-kernel, liliang.opensource,
qemu-devel, virtualization, linux-mm, aarcange, virtio-dev, willy,
quan.xu, nilal, riel, cornelia.huck, mhocko, LKML, amit.shah,
Paolo Bonzini, akpm, mgorman
In-Reply-To: <1513079759-14169-2-git-send-email-wei.w.wang@intel.com>
Matthew, Wei,
On Tue, Dec 12, 2017 at 12:55 PM, Wei Wang <wei.w.wang@intel.com> wrote:
> From: Matthew Wilcox <mawilcox@microsoft.com>
>
> The eXtensible Bitmap is a sparse bitmap representation which is
> efficient for set bits which tend to cluster. It supports up to
> 'unsigned long' worth of bits, and this commit adds the bare bones --
> xb_set_bit(), xb_clear_bit() and xb_test_bit().
>
> Signed-off-by: Wei Wang <wei.w.wang@intel.com>
> Cc: Matthew Wilcox <mawilcox@microsoft.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Michal Hocko <mhocko@kernel.org>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
[...]
> --- /dev/null
> +++ b/include/linux/xbitmap.h
> @@ -0,0 +1,52 @@
> +/*
> + * eXtensible Bitmaps
> + * Copyright (c) 2017 Microsoft Corporation <mawilcox@microsoft.com>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation; either version 2 of the
> + * License, or (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * eXtensible Bitmaps provide an unlimited-size sparse bitmap facility.
> + * All bits are initially zero.
> + */
Have you considered using the new SPDX ids here instead? eg. this
would come out as a top line this way:
> +/* SPDX-License-Identifer: GPL-2.0+ */
Overall you get less boilerplate comment and more code, so this is a
win-win for everyone. This would nicely remove the legalese
boilerplate with the same effect, unless you are a legalese lover of
course. See Thomas doc patches for extra details.... and while you are
it if you could spread the words in your team and use it for all past,
present and future contributions, that would be much appreciated.
And as a side benefit to me, it will help me save on paper and ink
ribbons supplies for my dot matrix line printer each time I print the
source code of the whole kernel. ;)
Thanks for your consideration there.
--
Cordially
Philippe Ombredanne
^ permalink raw reply
* [PATCH] virtio_mmio: fix devm cleanup
From: Mark Rutland @ 2017-12-12 12:53 UTC (permalink / raw)
To: linux-kernel
Cc: Mark Rutland, Cornelia Huck, weiping zhang, virtualization,
Michael S . Tsirkin
Recent rework of the virtio_mmio probe path balanced a devm_ioremap()
with an iounmap() rather than its devm variant. This ends up corrupting
the devm datastructures, and results in the following boot failure on
arm64 under QEMU 2.9.0:
[ 3.450397] ------------[ cut here ]------------
[ 3.453822] Trying to vfree() nonexistent vm area (00000000c05b4844)
[ 3.460534] WARNING: CPU: 1 PID: 1 at mm/vmalloc.c:1525 __vunmap+0x1b8/0x220
[ 3.475898] Kernel panic - not syncing: panic_on_warn set ...
[ 3.475898]
[ 3.493933] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.15.0-rc3 #1
[ 3.513109] Hardware name: linux,dummy-virt (DT)
[ 3.525382] Call trace:
[ 3.531683] dump_backtrace+0x0/0x368
[ 3.543921] show_stack+0x20/0x30
[ 3.547767] dump_stack+0x108/0x164
[ 3.559584] panic+0x25c/0x51c
[ 3.569184] __warn+0x29c/0x31c
[ 3.576023] report_bug+0x1d4/0x290
[ 3.586069] bug_handler.part.2+0x40/0x100
[ 3.597820] bug_handler+0x4c/0x88
[ 3.608400] brk_handler+0x11c/0x218
[ 3.613430] do_debug_exception+0xe8/0x318
[ 3.627370] el1_dbg+0x18/0x78
[ 3.634037] __vunmap+0x1b8/0x220
[ 3.648747] vunmap+0x6c/0xc0
[ 3.653864] __iounmap+0x44/0x58
[ 3.659771] devm_ioremap_release+0x34/0x68
[ 3.672983] release_nodes+0x404/0x880
[ 3.683543] devres_release_all+0x6c/0xe8
[ 3.695692] driver_probe_device+0x250/0x828
[ 3.706187] __driver_attach+0x190/0x210
[ 3.717645] bus_for_each_dev+0x14c/0x1f0
[ 3.728633] driver_attach+0x48/0x78
[ 3.740249] bus_add_driver+0x26c/0x5b8
[ 3.752248] driver_register+0x16c/0x398
[ 3.757211] __platform_driver_register+0xd8/0x128
[ 3.770860] virtio_mmio_init+0x1c/0x24
[ 3.782671] do_one_initcall+0xe0/0x398
[ 3.791890] kernel_init_freeable+0x594/0x660
[ 3.798514] kernel_init+0x18/0x190
[ 3.810220] ret_from_fork+0x10/0x18
To fix this, we can simply rip out the explicit cleanup that the devm
infrastructure will do for us when our probe function returns an error
code. We only need to ensure that we call put_device() if a call to
register_virtio_device() fails.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Fixes: 7eb781b1bbb7136f ("virtio_mmio: add cleanup for virtio_mmio_probe")
Cc: Cornelia Huck <cohuck@redhat.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: weiping zhang <zhangweiping@didichuxing.com>
Cc: virtualization@lists.linux-foundation.org
---
drivers/virtio/virtio_mmio.c | 36 +++++++++---------------------------
1 file changed, 9 insertions(+), 27 deletions(-)
diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index a9192fe4f345..793b1085967f 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -522,10 +522,8 @@ static int virtio_mmio_probe(struct platform_device *pdev)
return -EBUSY;
vm_dev = devm_kzalloc(&pdev->dev, sizeof(*vm_dev), GFP_KERNEL);
- if (!vm_dev) {
- rc = -ENOMEM;
- goto free_mem;
- }
+ if (!vm_dev)
+ return -ENOMEM;
vm_dev->vdev.dev.parent = &pdev->dev;
vm_dev->vdev.dev.release = virtio_mmio_release_dev;
@@ -535,17 +533,14 @@ static int virtio_mmio_probe(struct platform_device *pdev)
spin_lock_init(&vm_dev->lock);
vm_dev->base = devm_ioremap(&pdev->dev, mem->start, resource_size(mem));
- if (vm_dev->base == NULL) {
- rc = -EFAULT;
- goto free_vmdev;
- }
+ if (vm_dev->base == NULL)
+ return -EFAULT;
/* Check magic value */
magic = readl(vm_dev->base + VIRTIO_MMIO_MAGIC_VALUE);
if (magic != ('v' | 'i' << 8 | 'r' << 16 | 't' << 24)) {
dev_warn(&pdev->dev, "Wrong magic value 0x%08lx!\n", magic);
- rc = -ENODEV;
- goto unmap;
+ return -ENODEV;
}
/* Check device version */
@@ -553,8 +548,7 @@ static int virtio_mmio_probe(struct platform_device *pdev)
if (vm_dev->version < 1 || vm_dev->version > 2) {
dev_err(&pdev->dev, "Version %ld not supported!\n",
vm_dev->version);
- rc = -ENXIO;
- goto unmap;
+ return -ENXIO;
}
vm_dev->vdev.id.device = readl(vm_dev->base + VIRTIO_MMIO_DEVICE_ID);
@@ -563,8 +557,7 @@ static int virtio_mmio_probe(struct platform_device *pdev)
* virtio-mmio device with an ID 0 is a (dummy) placeholder
* with no function. End probing now with no error reported.
*/
- rc = -ENODEV;
- goto unmap;
+ return -ENODEV;
}
vm_dev->vdev.id.vendor = readl(vm_dev->base + VIRTIO_MMIO_VENDOR_ID);
@@ -590,20 +583,9 @@ static int virtio_mmio_probe(struct platform_device *pdev)
platform_set_drvdata(pdev, vm_dev);
rc = register_virtio_device(&vm_dev->vdev);
- if (rc) {
- iounmap(vm_dev->base);
- devm_release_mem_region(&pdev->dev, mem->start,
- resource_size(mem));
+ if (rc)
put_device(&vm_dev->vdev.dev);
- }
- return rc;
-unmap:
- iounmap(vm_dev->base);
-free_mem:
- devm_release_mem_region(&pdev->dev, mem->start,
- resource_size(mem));
-free_vmdev:
- devm_kfree(&pdev->dev, vm_dev);
+
return rc;
}
--
2.11.0
^ permalink raw reply related
* Re: [PATCH v18 10/10] virtio-balloon: don't report free pages when page poisoning is enabled
From: Wei Wang @ 2017-12-12 12:21 UTC (permalink / raw)
To: Michael S. Tsirkin
Cc: yang.zhang.wz, kvm, penguin-kernel, liliang.opensource,
qemu-devel, virtualization, linux-mm, aarcange, virtio-dev,
mawilcox, willy, quan.xu, nilal, riel, cornelia.huck, mhocko,
linux-kernel, amit.shah, pbonzini, akpm, mgorman
In-Reply-To: <20171211152258-mutt-send-email-mst@kernel.org>
On 12/11/2017 09:24 PM, Michael S. Tsirkin wrote:
> On Mon, Dec 11, 2017 at 02:38:45PM +0800, Wei Wang wrote:
>> On 12/01/2017 11:49 PM, Michael S. Tsirkin wrote:
>>> On Wed, Nov 29, 2017 at 09:55:26PM +0800, Wei Wang wrote:
>>>> The guest free pages should not be discarded by the live migration thread
>>>> when page poisoning is enabled with PAGE_POISONING_NO_SANITY=n, because
>>>> skipping the transfer of such poisoned free pages will trigger false
>>>> positive when new pages are allocated and checked on the destination.
>>>> This patch skips the reporting of free pages in the above case.
>>>>
>>>> Reported-by: Michael S. Tsirkin <mst@redhat.com>
>>>> Signed-off-by: Wei Wang <wei.w.wang@intel.com>
>>>> Cc: Michal Hocko <mhocko@suse.com>
>>>> ---
>>>> drivers/virtio/virtio_balloon.c | 4 +++-
>>>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
>>>> index 035bd3a..6ac4cff 100644
>>>> --- a/drivers/virtio/virtio_balloon.c
>>>> +++ b/drivers/virtio/virtio_balloon.c
>>>> @@ -652,7 +652,9 @@ static void report_free_page(struct work_struct *work)
>>>> /* Start by sending the obtained cmd id to the host with an outbuf */
>>>> send_one_desc(vb, vb->free_page_vq, virt_to_phys(&vb->start_cmd_id),
>>>> sizeof(uint32_t), false, true, false);
>>>> - walk_free_mem_block(vb, 0, &virtio_balloon_send_free_pages);
>>>> + if (!(page_poisoning_enabled() &&
>>>> + !IS_ENABLED(CONFIG_PAGE_POISONING_NO_SANITY)))
>>>> + walk_free_mem_block(vb, 0, &virtio_balloon_send_free_pages);
>>>> /*
>>>> * End by sending the stop id to the host with an outbuf. Use the
>>>> * non-batching mode here to trigger a kick after adding the stop id.
>>> PAGE_POISONING_ZERO is actually OK.
>>>
>>> But I really would prefer it that we still send pages to host,
>>> otherwise debugging becomes much harder.
>>>
>>> And it does not have to be completely useless, even though
>>> you can not discard them as they would be zero-filled then.
>>>
>>> How about a config field telling host what should be there in the free
>>> pages? This way even though host can not discard them, host can send
>>> them out without reading them, still a win.
>>>
>>>
>> Since this poison value comes with the free page reporting feature, how
>> about sending the poison value via the free_page_vq, along with the cmd id
>> in the outbuf? That is, use the following interface:
>>
>> struct virtio_balloon_free_page_vq_hdr {
>> bool page_poisoning;
>> __virtio32 poison_value;
>> __virtio32 cmd_id;
>> }
> Can we put the value in config space instead?
>
>> We need "bool page_poisoning" because "poison_value=0" doesn't tell whether
>> page poising is in use by the guest.
> Can we use a feature bit for this?
>
>> PAGE_POISONING_ZERO sets
>> "page_poisoning=true, poisoning_value=0", and the host will send the
>> 0-filled pages to the destination (if not sending 0-filled pages, the
>> destination host would offer non-zero pages to the guest)
> Why would it? Linux zeroes all pages on alloc.
>
Thanks, that is the case. I think we don't need a feature bit then.
Please have a check the v19 patches.
Best,
Wei
^ permalink raw reply
* [PATCH v19 7/7] virtio-balloon: don't report free pages when page poisoning is enabled
From: Wei Wang @ 2017-12-12 11:55 UTC (permalink / raw)
To: virtio-dev, linux-kernel, qemu-devel, virtualization, kvm,
linux-mm, mst, mhocko, akpm, mawilcox
Cc: aarcange, yang.zhang.wz, riel, penguin-kernel, liliang.opensource,
willy, amit.shah, quan.xu, cornelia.huck, pbonzini, nilal,
mgorman
In-Reply-To: <1513079759-14169-1-git-send-email-wei.w.wang@intel.com>
The guest free pages should not be discarded by the live migration thread
when page poisoning is enabled with PAGE_POISONING_NO_SANITY=n, because
skipping the transfer of such poisoned free pages will trigger false
positive when new pages are allocated and checked on the destination.
This patch adds a config field, poison_val. Guest writes to the config
field to tell the host about the poisoning value. The value will be 0 in
the following cases:
1) PAGE_POISONING_NO_SANITY is enabled;
2) page poisoning is disabled; or
3) PAGE_POISONING_ZERO is enabled.
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Suggested-by: Michael S. Tsirkin <mst@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
---
drivers/virtio/virtio_balloon.c | 8 ++++++++
include/uapi/linux/virtio_balloon.h | 2 ++
2 files changed, 10 insertions(+)
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 6e4f359..3050c9f 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -858,6 +858,7 @@ static struct file_system_type balloon_fs = {
static int virtballoon_probe(struct virtio_device *vdev)
{
struct virtio_balloon *vb;
+ __u32 poison_val;
int err;
if (!vdev->config->get) {
@@ -895,6 +896,13 @@ static int virtballoon_probe(struct virtio_device *vdev)
WQ_FREEZABLE | WQ_CPU_INTENSIVE, 0);
INIT_WORK(&vb->report_free_page_work, report_free_page);
vb->stop_cmd_id = VIRTIO_BALLOON_FREE_PAGE_REPORT_STOP_ID;
+ if (IS_ENABLED(CONFIG_PAGE_POISONING_NO_SANITY) ||
+ !page_poisoning_enabled())
+ poison_val = 0;
+ else
+ poison_val = PAGE_POISON;
+ virtio_cwrite(vb->vdev, struct virtio_balloon_config,
+ poison_val, &poison_val);
}
vb->nb.notifier_call = virtballoon_oom_notify;
diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h
index 58f1274..f270e9e 100644
--- a/include/uapi/linux/virtio_balloon.h
+++ b/include/uapi/linux/virtio_balloon.h
@@ -48,6 +48,8 @@ struct virtio_balloon_config {
__u32 actual;
/* Free page report command id, readonly by guest */
__u32 free_page_report_cmd_id;
+ /* Stores PAGE_POISON if page poisoning with sanity check is in use */
+ __u32 poison_val;
};
#define VIRTIO_BALLOON_S_SWAP_IN 0 /* Amount of memory swapped in */
--
2.7.4
^ permalink raw reply related
* [PATCH v19 6/7] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_VQ
From: Wei Wang @ 2017-12-12 11:55 UTC (permalink / raw)
To: virtio-dev, linux-kernel, qemu-devel, virtualization, kvm,
linux-mm, mst, mhocko, akpm, mawilcox
Cc: aarcange, yang.zhang.wz, riel, penguin-kernel, liliang.opensource,
willy, amit.shah, quan.xu, cornelia.huck, pbonzini, nilal,
mgorman
In-Reply-To: <1513079759-14169-1-git-send-email-wei.w.wang@intel.com>
Negotiation of the VIRTIO_BALLOON_F_FREE_PAGE_VQ feature indicates the
support of reporting hints of guest free pages to host via virtio-balloon.
Host requests the guest to report free pages by sending a new cmd
id to the guest via the free_page_report_cmd_id configuration register.
When the guest starts to report, the first element added to the free page
vq is the cmd id given by host. When the guest finishes the reporting
of all the free pages, VIRTIO_BALLOON_FREE_PAGE_REPORT_STOP_ID is added
to the vq to tell host that the reporting is done. Host may also requests
the guest to stop the reporting in advance by sending the stop cmd id to
the guest via the configuration register.
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Signed-off-by: Liang Li <liang.z.li@intel.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
---
drivers/virtio/virtio_balloon.c | 202 ++++++++++++++++++++++++++++++------
include/uapi/linux/virtio_balloon.h | 4 +
2 files changed, 174 insertions(+), 32 deletions(-)
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 8e840a2..6e4f359 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -55,7 +55,12 @@ static struct vfsmount *balloon_mnt;
struct virtio_balloon {
struct virtio_device *vdev;
- struct virtqueue *inflate_vq, *deflate_vq, *stats_vq;
+ struct virtqueue *inflate_vq, *deflate_vq, *stats_vq, *free_page_vq;
+
+ /* Balloon's own wq for cpu-intensive work items */
+ struct workqueue_struct *balloon_wq;
+ /* The free page reporting work item submitted to the balloon wq */
+ struct work_struct report_free_page_work;
/* The balloon servicing is delegated to a freezable workqueue. */
struct work_struct update_balloon_stats_work;
@@ -65,6 +70,13 @@ struct virtio_balloon {
spinlock_t stop_update_lock;
bool stop_update;
+ /* Start to report free pages */
+ bool report_free_page;
+ /* Stores the cmd id given by host to start the free page reporting */
+ uint32_t start_cmd_id;
+ /* Stores STOP_ID as a sign to tell host that the reporting is done */
+ uint32_t stop_cmd_id;
+
/* Waiting for host to ack the pages we released. */
wait_queue_head_t acked;
@@ -189,6 +201,28 @@ static void batch_balloon_page_sg(struct virtio_balloon *vb,
kick_and_wait(vq, vb->acked);
}
+static void batch_free_page_sg(struct virtqueue *vq,
+ unsigned long pfn,
+ uint32_t len)
+{
+ add_one_sg(vq, pfn, len);
+
+ /* Batch till the vq is full */
+ if (!vq->num_free)
+ virtqueue_kick(vq);
+}
+
+static void send_cmd_id(struct virtio_balloon *vb, void *addr)
+{
+ struct scatterlist sg;
+ int err;
+
+ sg_init_one(&sg, addr, sizeof(uint32_t));
+ err = virtqueue_add_outbuf(vb->free_page_vq, &sg, 1, vb, GFP_KERNEL);
+ BUG_ON(err);
+ virtqueue_kick(vb->free_page_vq);
+}
+
/*
* Send balloon pages in sgs to host. The balloon pages are recorded in the
* page xbitmap. Each bit in the bitmap corresponds to a page of PAGE_SIZE.
@@ -496,17 +530,6 @@ static void stats_handle_request(struct virtio_balloon *vb)
virtqueue_kick(vq);
}
-static void virtballoon_changed(struct virtio_device *vdev)
-{
- struct virtio_balloon *vb = vdev->priv;
- unsigned long flags;
-
- spin_lock_irqsave(&vb->stop_update_lock, flags);
- if (!vb->stop_update)
- queue_work(system_freezable_wq, &vb->update_balloon_size_work);
- spin_unlock_irqrestore(&vb->stop_update_lock, flags);
-}
-
static inline s64 towards_target(struct virtio_balloon *vb)
{
s64 target;
@@ -523,6 +546,36 @@ static inline s64 towards_target(struct virtio_balloon *vb)
return target - vb->num_pages;
}
+static void virtballoon_changed(struct virtio_device *vdev)
+{
+ struct virtio_balloon *vb = vdev->priv;
+ unsigned long flags;
+ __u32 cmd_id;
+ s64 diff = towards_target(vb);
+
+ if (diff) {
+ spin_lock_irqsave(&vb->stop_update_lock, flags);
+ if (!vb->stop_update)
+ queue_work(system_freezable_wq,
+ &vb->update_balloon_size_work);
+ spin_unlock_irqrestore(&vb->stop_update_lock, flags);
+ }
+
+ virtio_cread(vb->vdev, struct virtio_balloon_config,
+ free_page_report_cmd_id, &cmd_id);
+ if (cmd_id == VIRTIO_BALLOON_FREE_PAGE_REPORT_STOP_ID) {
+ WRITE_ONCE(vb->report_free_page, false);
+ } else if (cmd_id != vb->start_cmd_id) {
+ /*
+ * Host requests to start the reporting by sending a new cmd
+ * id.
+ */
+ WRITE_ONCE(vb->report_free_page, true);
+ vb->start_cmd_id = cmd_id;
+ queue_work(vb->balloon_wq, &vb->report_free_page_work);
+ }
+}
+
static void update_balloon_size(struct virtio_balloon *vb)
{
u32 actual = vb->num_pages;
@@ -600,40 +653,116 @@ static void update_balloon_size_func(struct work_struct *work)
static int init_vqs(struct virtio_balloon *vb)
{
- struct virtqueue *vqs[3];
- vq_callback_t *callbacks[] = { balloon_ack, balloon_ack, stats_request };
- static const char * const names[] = { "inflate", "deflate", "stats" };
- int err, nvqs;
+ struct virtqueue **vqs;
+ vq_callback_t **callbacks;
+ const char **names;
+ struct scatterlist sg;
+ int i, nvqs, err = -ENOMEM;
+
+ /* Inflateq and deflateq are used unconditionally */
+ nvqs = 2;
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ))
+ nvqs++;
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_VQ))
+ nvqs++;
+
+ /* Allocate space for find_vqs parameters */
+ vqs = kcalloc(nvqs, sizeof(*vqs), GFP_KERNEL);
+ if (!vqs)
+ goto err_vq;
+ callbacks = kmalloc_array(nvqs, sizeof(*callbacks), GFP_KERNEL);
+ if (!callbacks)
+ goto err_callback;
+ names = kmalloc_array(nvqs, sizeof(*names), GFP_KERNEL);
+ if (!names)
+ goto err_names;
+
+ callbacks[0] = balloon_ack;
+ names[0] = "inflate";
+ callbacks[1] = balloon_ack;
+ names[1] = "deflate";
+
+ i = 2;
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
+ callbacks[i] = stats_request;
+ names[i] = "stats";
+ i++;
+ }
- /*
- * We expect two virtqueues: inflate and deflate, and
- * optionally stat.
- */
- nvqs = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ) ? 3 : 2;
- err = virtio_find_vqs(vb->vdev, nvqs, vqs, callbacks, names, NULL);
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_VQ)) {
+ callbacks[i] = NULL;
+ names[i] = "free_page_vq";
+ }
+
+ err = vb->vdev->config->find_vqs(vb->vdev, nvqs, vqs, callbacks, names,
+ NULL, NULL);
if (err)
- return err;
+ goto err_find;
vb->inflate_vq = vqs[0];
vb->deflate_vq = vqs[1];
+ i = 2;
if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_STATS_VQ)) {
- struct scatterlist sg;
- unsigned int num_stats;
- vb->stats_vq = vqs[2];
-
+ vb->stats_vq = vqs[i++];
/*
* Prime this virtqueue with one buffer so the hypervisor can
* use it to signal us later (it can't be broken yet!).
*/
- num_stats = update_balloon_stats(vb);
-
- sg_init_one(&sg, vb->stats, sizeof(vb->stats[0]) * num_stats);
+ sg_init_one(&sg, vb->stats, sizeof(vb->stats));
if (virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb, GFP_KERNEL)
- < 0)
- BUG();
+ < 0) {
+ dev_warn(&vb->vdev->dev, "%s: add stat_vq failed\n",
+ __func__);
+ goto err_find;
+ }
virtqueue_kick(vb->stats_vq);
}
+
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_FREE_PAGE_VQ))
+ vb->free_page_vq = vqs[i];
+
+ kfree(names);
+ kfree(callbacks);
+ kfree(vqs);
return 0;
+
+err_find:
+ kfree(names);
+err_names:
+ kfree(callbacks);
+err_callback:
+ kfree(vqs);
+err_vq:
+ return err;
+}
+
+static bool virtio_balloon_send_free_pages(void *opaque, unsigned long pfn,
+ unsigned long nr_pages)
+{
+ struct virtio_balloon *vb = (struct virtio_balloon *)opaque;
+ uint32_t len = nr_pages << PAGE_SHIFT;
+
+ if (!READ_ONCE(vb->report_free_page))
+ return false;
+
+ batch_free_page_sg(vb->free_page_vq, pfn, len);
+
+ return true;
+}
+
+static void report_free_page(struct work_struct *work)
+{
+ struct virtio_balloon *vb;
+
+ vb = container_of(work, struct virtio_balloon, report_free_page_work);
+ /* Start by sending the obtained cmd id to the host with an outbuf */
+ send_cmd_id(vb, &vb->start_cmd_id);
+ walk_free_mem_block(vb, 0, &virtio_balloon_send_free_pages);
+ /*
+ * End by sending the stop id to the host with an outbuf. Use the
+ * non-batching mode here to trigger a kick after adding the stop id.
+ */
+ send_cmd_id(vb, &vb->stop_cmd_id);
}
#ifdef CONFIG_BALLOON_COMPACTION
@@ -761,6 +890,13 @@ static int virtballoon_probe(struct virtio_device *vdev)
if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_SG))
xb_init(&vb->page_xb);
+ if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_VQ)) {
+ vb->balloon_wq = alloc_workqueue("balloon-wq",
+ WQ_FREEZABLE | WQ_CPU_INTENSIVE, 0);
+ INIT_WORK(&vb->report_free_page_work, report_free_page);
+ vb->stop_cmd_id = VIRTIO_BALLOON_FREE_PAGE_REPORT_STOP_ID;
+ }
+
vb->nb.notifier_call = virtballoon_oom_notify;
vb->nb.priority = VIRTBALLOON_OOM_NOTIFY_PRIORITY;
err = register_oom_notifier(&vb->nb);
@@ -825,6 +961,7 @@ static void virtballoon_remove(struct virtio_device *vdev)
spin_unlock_irq(&vb->stop_update_lock);
cancel_work_sync(&vb->update_balloon_size_work);
cancel_work_sync(&vb->update_balloon_stats_work);
+ cancel_work_sync(&vb->report_free_page_work);
remove_common(vb);
#ifdef CONFIG_BALLOON_COMPACTION
@@ -878,6 +1015,7 @@ static unsigned int features[] = {
VIRTIO_BALLOON_F_STATS_VQ,
VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
VIRTIO_BALLOON_F_SG,
+ VIRTIO_BALLOON_F_FREE_PAGE_VQ,
};
static struct virtio_driver virtio_balloon_driver = {
diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h
index 37780a7..58f1274 100644
--- a/include/uapi/linux/virtio_balloon.h
+++ b/include/uapi/linux/virtio_balloon.h
@@ -35,15 +35,19 @@
#define VIRTIO_BALLOON_F_STATS_VQ 1 /* Memory Stats virtqueue */
#define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 2 /* Deflate balloon on OOM */
#define VIRTIO_BALLOON_F_SG 3 /* Use sg instead of PFN lists */
+#define VIRTIO_BALLOON_F_FREE_PAGE_VQ 4 /* VQ to report free pages */
/* Size of a PFN in the balloon interface. */
#define VIRTIO_BALLOON_PFN_SHIFT 12
+#define VIRTIO_BALLOON_FREE_PAGE_REPORT_STOP_ID 0
struct virtio_balloon_config {
/* Number of pages host wants Guest to give up. */
__u32 num_pages;
/* Number of pages we've actually got in balloon. */
__u32 actual;
+ /* Free page report command id, readonly by guest */
+ __u32 free_page_report_cmd_id;
};
#define VIRTIO_BALLOON_S_SWAP_IN 0 /* Amount of memory swapped in */
--
2.7.4
^ permalink raw reply related
* [PATCH v19 5/7] mm: support reporting free page blocks
From: Wei Wang @ 2017-12-12 11:55 UTC (permalink / raw)
To: virtio-dev, linux-kernel, qemu-devel, virtualization, kvm,
linux-mm, mst, mhocko, akpm, mawilcox
Cc: aarcange, yang.zhang.wz, riel, penguin-kernel, liliang.opensource,
willy, amit.shah, quan.xu, cornelia.huck, pbonzini, nilal,
mgorman
In-Reply-To: <1513079759-14169-1-git-send-email-wei.w.wang@intel.com>
This patch adds support to walk through the free page blocks in the
system and report them via a callback function. Some page blocks may
leave the free list after zone->lock is released, so it is the caller's
responsibility to either detect or prevent the use of such pages.
One use example of this patch is to accelerate live migration by skipping
the transfer of free pages reported from the guest. A popular method used
by the hypervisor to track which part of memory is written during live
migration is to write-protect all the guest memory. So, those pages that
are reported as free pages but are written after the report function
returns will be captured by the hypervisor, and they will be added to the
next round of memory transfer.
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Signed-off-by: Liang Li <liang.z.li@intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Michal Hocko <mhocko@kernel.org>
---
include/linux/mm.h | 6 ++++
mm/page_alloc.c | 91 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 97 insertions(+)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ea818ff..b3077dd 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1938,6 +1938,12 @@ extern void free_area_init_node(int nid, unsigned long * zones_size,
unsigned long zone_start_pfn, unsigned long *zholes_size);
extern void free_initmem(void);
+extern void walk_free_mem_block(void *opaque,
+ int min_order,
+ bool (*report_pfn_range)(void *opaque,
+ unsigned long pfn,
+ unsigned long num));
+
/*
* Free reserved pages within range [PAGE_ALIGN(start), end & PAGE_MASK)
* into the buddy system. The freed pages will be poisoned with pattern
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 73f5d45..0de461d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4888,6 +4888,97 @@ void show_free_areas(unsigned int filter, nodemask_t *nodemask)
show_swap_cache_info();
}
+/*
+ * Walk through a free page list and report the found pfn range via the
+ * callback.
+ *
+ * Return false if the callback requests to stop reporting. Otherwise,
+ * return true.
+ */
+static bool walk_free_page_list(void *opaque,
+ struct zone *zone,
+ int order,
+ enum migratetype mt,
+ bool (*report_pfn_range)(void *,
+ unsigned long,
+ unsigned long))
+{
+ struct page *page;
+ struct list_head *list;
+ unsigned long pfn, flags;
+ bool ret;
+
+ spin_lock_irqsave(&zone->lock, flags);
+ list = &zone->free_area[order].free_list[mt];
+ list_for_each_entry(page, list, lru) {
+ pfn = page_to_pfn(page);
+ ret = report_pfn_range(opaque, pfn, 1 << order);
+ if (!ret)
+ break;
+ }
+ spin_unlock_irqrestore(&zone->lock, flags);
+
+ return ret;
+}
+
+/**
+ * walk_free_mem_block - Walk through the free page blocks in the system
+ * @opaque: the context passed from the caller
+ * @min_order: the minimum order of free lists to check
+ * @report_pfn_range: the callback to report the pfn range of the free pages
+ *
+ * If the callback returns false, stop iterating the list of free page blocks.
+ * Otherwise, continue to report.
+ *
+ * Please note that there are no locking guarantees for the callback and
+ * that the reported pfn range might be freed or disappear after the
+ * callback returns so the caller has to be very careful how it is used.
+ *
+ * The callback itself must not sleep or perform any operations which would
+ * require any memory allocations directly (not even GFP_NOWAIT/GFP_ATOMIC)
+ * or via any lock dependency. It is generally advisable to implement
+ * the callback as simple as possible and defer any heavy lifting to a
+ * different context.
+ *
+ * There is no guarantee that each free range will be reported only once
+ * during one walk_free_mem_block invocation.
+ *
+ * pfn_to_page on the given range is strongly discouraged and if there is
+ * an absolute need for that make sure to contact MM people to discuss
+ * potential problems.
+ *
+ * The function itself might sleep so it cannot be called from atomic
+ * contexts.
+ *
+ * In general low orders tend to be very volatile and so it makes more
+ * sense to query larger ones first for various optimizations which like
+ * ballooning etc... This will reduce the overhead as well.
+ */
+void walk_free_mem_block(void *opaque,
+ int min_order,
+ bool (*report_pfn_range)(void *opaque,
+ unsigned long pfn,
+ unsigned long num))
+{
+ struct zone *zone;
+ int order;
+ enum migratetype mt;
+ bool ret;
+
+ for_each_populated_zone(zone) {
+ for (order = MAX_ORDER - 1; order >= min_order; order--) {
+ for (mt = 0; mt < MIGRATE_TYPES; mt++) {
+ ret = walk_free_page_list(opaque, zone,
+ order, mt,
+ report_pfn_range);
+ if (!ret)
+ return;
+ }
+ }
+ }
+}
+EXPORT_SYMBOL_GPL(walk_free_mem_block);
+
static void zoneref_set_zone(struct zone *zone, struct zoneref *zoneref)
{
zoneref->zone = zone;
--
2.7.4
^ permalink raw reply related
* [PATCH v19 4/7] virtio-balloon: VIRTIO_BALLOON_F_SG
From: Wei Wang @ 2017-12-12 11:55 UTC (permalink / raw)
To: virtio-dev, linux-kernel, qemu-devel, virtualization, kvm,
linux-mm, mst, mhocko, akpm, mawilcox
Cc: aarcange, yang.zhang.wz, riel, penguin-kernel, liliang.opensource,
willy, amit.shah, quan.xu, cornelia.huck, pbonzini, nilal,
mgorman
In-Reply-To: <1513079759-14169-1-git-send-email-wei.w.wang@intel.com>
Add a new feature, VIRTIO_BALLOON_F_SG, which enables the transfer of
balloon (i.e. inflated/deflated) pages using scatter-gather lists to the
host.
The implementation of the previous virtio-balloon is not very efficient,
because the balloon pages are transferred to the host by one array each
time. Here is the breakdown of the time in percentage spent on each step
of the balloon inflating process (inflating 7GB of an 8GB idle guest).
1) allocating pages (6.5%)
2) sending PFNs to host (68.3%)
3) address translation (6.1%)
4) madvise (19%)
It takes about 4126ms for the inflating process to complete. The above
profiling shows that the bottlenecks are stage 2) and stage 4).
This patch optimizes step 2) by transferring pages to host in sgs. An sg
describes a chunk of guest physically continuous pages. With this
mechanism, step 4) can also be optimized by doing address translation and
madvise() in chunks rather than page by page.
With this new feature, the above ballooning process takes ~490ms resulting
in an improvement of ~88%.
TODO:
- optimize stage 1) by allocating/freeing a chunk of pages instead of a
single page each time.
- sort the internal balloon page queue.
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Signed-off-by: Liang Li <liang.z.li@intel.com>
Suggested-by: Michael S. Tsirkin <mst@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
drivers/virtio/virtio_balloon.c | 232 +++++++++++++++++++++++++++++++++---
include/uapi/linux/virtio_balloon.h | 1 +
2 files changed, 215 insertions(+), 18 deletions(-)
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index a1fb52c..8e840a2 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -32,6 +32,8 @@
#include <linux/mm.h>
#include <linux/mount.h>
#include <linux/magic.h>
+#include <linux/xbitmap.h>
+#include <asm/page.h>
/*
* Balloon device works in 4K page units. So each page is pointed to by
@@ -79,6 +81,9 @@ struct virtio_balloon {
/* Synchronize access/update to this struct virtio_balloon elements */
struct mutex balloon_lock;
+ /* The xbitmap used to record balloon pages */
+ struct xb page_xb;
+
/* The array of pfns we tell the Host about. */
unsigned int num_pfns;
__virtio32 pfns[VIRTIO_BALLOON_ARRAY_PFNS_MAX];
@@ -141,15 +146,127 @@ static void set_page_pfns(struct virtio_balloon *vb,
page_to_balloon_pfn(page) + i);
}
+static void kick_and_wait(struct virtqueue *vq, wait_queue_head_t wq_head)
+{
+ unsigned int len;
+
+ virtqueue_kick(vq);
+ wait_event(wq_head, virtqueue_get_buf(vq, &len));
+}
+
+static void add_one_sg(struct virtqueue *vq, unsigned long pfn, uint32_t len)
+{
+ struct scatterlist sg;
+ unsigned int unused;
+ int err;
+
+ sg_init_table(&sg, 1);
+ sg_set_page(&sg, pfn_to_page(pfn), len, 0);
+
+ /* Detach all the used buffers from the vq */
+ while (virtqueue_get_buf(vq, &unused))
+ ;
+
+ err = virtqueue_add_inbuf(vq, &sg, 1, vq, GFP_KERNEL);
+ /*
+ * This is expected to never fail: there is always at least 1 entry
+ * available on the vq, because when the vq is full the worker thread
+ * that adds the sg will be put into sleep until at least 1 entry is
+ * available to use.
+ */
+ BUG_ON(err);
+}
+
+static void batch_balloon_page_sg(struct virtio_balloon *vb,
+ struct virtqueue *vq,
+ unsigned long pfn,
+ uint32_t len)
+{
+ add_one_sg(vq, pfn, len);
+
+ /* Batch till the vq is full */
+ if (!vq->num_free)
+ kick_and_wait(vq, vb->acked);
+}
+
+/*
+ * Send balloon pages in sgs to host. The balloon pages are recorded in the
+ * page xbitmap. Each bit in the bitmap corresponds to a page of PAGE_SIZE.
+ * The page xbitmap is searched for continuous "1" bits, which correspond
+ * to continuous pages, to chunk into sgs.
+ *
+ * @page_xb_start and @page_xb_end form the range of bits in the xbitmap that
+ * need to be searched.
+ */
+static void tell_host_sgs(struct virtio_balloon *vb,
+ struct virtqueue *vq,
+ unsigned long page_xb_start,
+ unsigned long page_xb_end)
+{
+ unsigned long pfn_start, pfn_end;
+ uint32_t max_len = round_down(UINT_MAX, PAGE_SIZE);
+ uint64_t len;
+
+ pfn_start = page_xb_start;
+ while (pfn_start < page_xb_end) {
+ pfn_start = xb_find_next_set_bit(&vb->page_xb, pfn_start,
+ page_xb_end + 1);
+ if (pfn_start == page_xb_end + 1)
+ break;
+ pfn_end = xb_find_next_zero_bit(&vb->page_xb,
+ pfn_start,
+ page_xb_end + 1);
+ len = (pfn_end - pfn_start) << PAGE_SHIFT;
+ while (len > max_len) {
+ batch_balloon_page_sg(vb, vq, pfn_start, max_len);
+ pfn_start += max_len >> PAGE_SHIFT;
+ len -= max_len;
+ }
+ batch_balloon_page_sg(vb, vq, pfn_start, (uint32_t)len);
+ pfn_start = pfn_end + 1;
+ }
+
+ /*
+ * The last few sgs may not reach the batch size, but need a kick to
+ * notify the device to handle them.
+ */
+ if (vq->num_free != virtqueue_get_vring_size(vq))
+ kick_and_wait(vq, vb->acked);
+
+ xb_clear_bit_range(&vb->page_xb, page_xb_start, page_xb_end);
+}
+
+static inline int xb_set_page(struct virtio_balloon *vb,
+ struct page *page,
+ unsigned long *pfn_min,
+ unsigned long *pfn_max)
+{
+ unsigned long pfn = page_to_pfn(page);
+ int ret;
+
+ *pfn_min = min(pfn, *pfn_min);
+ *pfn_max = max(pfn, *pfn_max);
+
+ do {
+ ret = xb_preload_and_set_bit(&vb->page_xb, pfn,
+ GFP_NOWAIT | __GFP_NOWARN);
+ } while (unlikely(ret == -EAGAIN));
+
+ return ret;
+}
+
static unsigned fill_balloon(struct virtio_balloon *vb, size_t num)
{
unsigned num_allocated_pages;
unsigned num_pfns;
struct page *page;
LIST_HEAD(pages);
+ bool use_sg = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_SG);
+ unsigned long pfn_max = 0, pfn_min = ULONG_MAX;
/* We can only do one array worth at a time. */
- num = min(num, ARRAY_SIZE(vb->pfns));
+ if (!use_sg)
+ num = min(num, ARRAY_SIZE(vb->pfns));
for (num_pfns = 0; num_pfns < num;
num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE) {
@@ -173,8 +290,15 @@ static unsigned fill_balloon(struct virtio_balloon *vb, size_t num)
while ((page = balloon_page_pop(&pages))) {
balloon_page_enqueue(&vb->vb_dev_info, page);
+ if (use_sg) {
+ if (xb_set_page(vb, page, &pfn_min, &pfn_max) < 0) {
+ __free_page(page);
+ continue;
+ }
+ } else {
+ set_page_pfns(vb, vb->pfns + vb->num_pfns, page);
+ }
- set_page_pfns(vb, vb->pfns + vb->num_pfns, page);
vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE;
if (!virtio_has_feature(vb->vdev,
VIRTIO_BALLOON_F_DEFLATE_ON_OOM))
@@ -184,8 +308,12 @@ static unsigned fill_balloon(struct virtio_balloon *vb, size_t num)
num_allocated_pages = vb->num_pfns;
/* Did we get any? */
- if (vb->num_pfns != 0)
- tell_host(vb, vb->inflate_vq);
+ if (vb->num_pfns) {
+ if (use_sg)
+ tell_host_sgs(vb, vb->inflate_vq, pfn_min, pfn_max);
+ else
+ tell_host(vb, vb->inflate_vq);
+ }
mutex_unlock(&vb->balloon_lock);
return num_allocated_pages;
@@ -211,9 +339,12 @@ static unsigned leak_balloon(struct virtio_balloon *vb, size_t num)
struct page *page;
struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;
LIST_HEAD(pages);
+ bool use_sg = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_SG);
+ unsigned long pfn_max = 0, pfn_min = ULONG_MAX;
- /* We can only do one array worth at a time. */
- num = min(num, ARRAY_SIZE(vb->pfns));
+ /* Traditionally, we can only do one array worth at a time. */
+ if (!use_sg)
+ num = min(num, ARRAY_SIZE(vb->pfns));
mutex_lock(&vb->balloon_lock);
/* We can't release more pages than taken */
@@ -223,7 +354,14 @@ static unsigned leak_balloon(struct virtio_balloon *vb, size_t num)
page = balloon_page_dequeue(vb_dev_info);
if (!page)
break;
- set_page_pfns(vb, vb->pfns + vb->num_pfns, page);
+ if (use_sg) {
+ if (xb_set_page(vb, page, &pfn_min, &pfn_max) < 0) {
+ balloon_page_enqueue(&vb->vb_dev_info, page);
+ break;
+ }
+ } else {
+ set_page_pfns(vb, vb->pfns + vb->num_pfns, page);
+ }
list_add(&page->lru, &pages);
vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE;
}
@@ -234,13 +372,55 @@ static unsigned leak_balloon(struct virtio_balloon *vb, size_t num)
* virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST);
* is true, we *have* to do it in this order
*/
- if (vb->num_pfns != 0)
- tell_host(vb, vb->deflate_vq);
+ if (vb->num_pfns) {
+ if (use_sg)
+ tell_host_sgs(vb, vb->deflate_vq, pfn_min, pfn_max);
+ else
+ tell_host(vb, vb->deflate_vq);
+ }
release_pages_balloon(vb, &pages);
mutex_unlock(&vb->balloon_lock);
return num_freed_pages;
}
+/*
+ * The regular leak_balloon() with VIRTIO_BALLOON_F_SG needs memory allocation
+ * for xbitmap, which is not suitable for the oom case. This function does not
+ * use xbitmap to chunk pages, so it can be used by oom notifier to deflate
+ * pages when VIRTIO_BALLOON_F_SG is negotiated.
+ */
+static unsigned int leak_balloon_sg_oom(struct virtio_balloon *vb)
+{
+ unsigned int n;
+ struct page *page;
+ struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;
+ struct virtqueue *vq = vb->deflate_vq;
+ LIST_HEAD(pages);
+
+ mutex_lock(&vb->balloon_lock);
+ for (n = 0; n < oom_pages; n++) {
+ page = balloon_page_dequeue(vb_dev_info);
+ if (!page)
+ break;
+
+ list_add(&page->lru, &pages);
+ vb->num_pages -= VIRTIO_BALLOON_PAGES_PER_PAGE;
+ batch_balloon_page_sg(vb, vb->deflate_vq, page_to_pfn(page),
+ PAGE_SIZE);
+ release_pages_balloon(vb, &pages);
+ }
+
+ /*
+ * The last few sgs may not reach the batch size, but need a kick to
+ * notify the device to handle them.
+ */
+ if (vq->num_free != virtqueue_get_vring_size(vq))
+ kick_and_wait(vq, vb->acked);
+ mutex_unlock(&vb->balloon_lock);
+
+ return n;
+}
+
static inline void update_stat(struct virtio_balloon *vb, int idx,
u16 tag, u64 val)
{
@@ -380,7 +560,10 @@ static int virtballoon_oom_notify(struct notifier_block *self,
return NOTIFY_OK;
freed = parm;
- num_freed_pages = leak_balloon(vb, oom_pages);
+ if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_SG))
+ num_freed_pages = leak_balloon_sg_oom(vb);
+ else
+ num_freed_pages = leak_balloon(vb, oom_pages);
update_balloon_size(vb);
*freed += num_freed_pages;
@@ -477,6 +660,7 @@ static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info,
{
struct virtio_balloon *vb = container_of(vb_dev_info,
struct virtio_balloon, vb_dev_info);
+ bool use_sg = virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_SG);
unsigned long flags;
/*
@@ -498,16 +682,24 @@ static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info,
vb_dev_info->isolated_pages--;
__count_vm_event(BALLOON_MIGRATE);
spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags);
- vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
- set_page_pfns(vb, vb->pfns, newpage);
- tell_host(vb, vb->inflate_vq);
-
+ if (use_sg) {
+ add_one_sg(vb->inflate_vq, page_to_pfn(newpage), PAGE_SIZE);
+ kick_and_wait(vb->inflate_vq, vb->acked);
+ } else {
+ vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
+ set_page_pfns(vb, vb->pfns, newpage);
+ tell_host(vb, vb->inflate_vq);
+ }
/* balloon's page migration 2nd step -- deflate "page" */
balloon_page_delete(page);
- vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
- set_page_pfns(vb, vb->pfns, page);
- tell_host(vb, vb->deflate_vq);
-
+ if (use_sg) {
+ add_one_sg(vb->deflate_vq, page_to_pfn(page), PAGE_SIZE);
+ kick_and_wait(vb->deflate_vq, vb->acked);
+ } else {
+ vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
+ set_page_pfns(vb, vb->pfns, page);
+ tell_host(vb, vb->deflate_vq);
+ }
mutex_unlock(&vb->balloon_lock);
put_page(page); /* balloon reference */
@@ -566,6 +758,9 @@ static int virtballoon_probe(struct virtio_device *vdev)
if (err)
goto out_free_vb;
+ if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_SG))
+ xb_init(&vb->page_xb);
+
vb->nb.notifier_call = virtballoon_oom_notify;
vb->nb.priority = VIRTBALLOON_OOM_NOTIFY_PRIORITY;
err = register_oom_notifier(&vb->nb);
@@ -682,6 +877,7 @@ static unsigned int features[] = {
VIRTIO_BALLOON_F_MUST_TELL_HOST,
VIRTIO_BALLOON_F_STATS_VQ,
VIRTIO_BALLOON_F_DEFLATE_ON_OOM,
+ VIRTIO_BALLOON_F_SG,
};
static struct virtio_driver virtio_balloon_driver = {
diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h
index 343d7dd..37780a7 100644
--- a/include/uapi/linux/virtio_balloon.h
+++ b/include/uapi/linux/virtio_balloon.h
@@ -34,6 +34,7 @@
#define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */
#define VIRTIO_BALLOON_F_STATS_VQ 1 /* Memory Stats virtqueue */
#define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 2 /* Deflate balloon on OOM */
+#define VIRTIO_BALLOON_F_SG 3 /* Use sg instead of PFN lists */
/* Size of a PFN in the balloon interface. */
#define VIRTIO_BALLOON_PFN_SHIFT 12
--
2.7.4
^ permalink raw reply related
* [PATCH v19 3/7] xbitmap: add more operations
From: Wei Wang @ 2017-12-12 11:55 UTC (permalink / raw)
To: virtio-dev, linux-kernel, qemu-devel, virtualization, kvm,
linux-mm, mst, mhocko, akpm, mawilcox
Cc: aarcange, yang.zhang.wz, riel, penguin-kernel, liliang.opensource,
willy, amit.shah, quan.xu, cornelia.huck, pbonzini, nilal,
mgorman
In-Reply-To: <1513079759-14169-1-git-send-email-wei.w.wang@intel.com>
This patch adds support to find next 1 or 0 bit in a xbmitmap range and
clear a range of bits.
More possible optimizations to add in the future:
1) xb_set_bit_range: set a range of bits.
2) when searching a bit, if the bit is not found in the slot, move on to
the next slot directly.
3) add tags to help searching.
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Suggested-by: Matthew Wilcox <mawilcox@microsoft.com>
---
include/linux/xbitmap.h | 8 +-
lib/xbitmap.c | 229 +++++++++++++++++++++++++++++++++++++++++++
tools/include/linux/bitmap.h | 34 +++++++
tools/include/linux/kernel.h | 2 +
4 files changed, 272 insertions(+), 1 deletion(-)
diff --git a/include/linux/xbitmap.h b/include/linux/xbitmap.h
index b4d8375..eddf0d5e 100644
--- a/include/linux/xbitmap.h
+++ b/include/linux/xbitmap.h
@@ -33,8 +33,14 @@ static inline void xb_init(struct xb *xb)
}
int xb_set_bit(struct xb *xb, unsigned long bit);
+int xb_preload_and_set_bit(struct xb *xb, unsigned long bit, gfp_t gfp);
bool xb_test_bit(const struct xb *xb, unsigned long bit);
-int xb_clear_bit(struct xb *xb, unsigned long bit);
+void xb_clear_bit(struct xb *xb, unsigned long bit);
+unsigned long xb_find_next_set_bit(struct xb *xb, unsigned long start,
+ unsigned long end);
+unsigned long xb_find_next_zero_bit(struct xb *xb, unsigned long start,
+ unsigned long end);
+void xb_clear_bit_range(struct xb *xb, unsigned long start, unsigned long end);
static inline bool xb_empty(const struct xb *xb)
{
diff --git a/lib/xbitmap.c b/lib/xbitmap.c
index 182aa29..10df879 100644
--- a/lib/xbitmap.c
+++ b/lib/xbitmap.c
@@ -3,6 +3,13 @@
#include <linux/bitmap.h>
#include <linux/slab.h>
+/*
+ * Developer notes: locks are required to gurantee there is no concurrent
+ * calls of xb_set_bit, xb_clear_bit, xb_clear_bit_range, xb_test_bit,
+ * xb_find_next_set_bit, or xb_find_next_clear_bit to operate on the same
+ * ida bitamp.
+ */
+
/**
* xb_set_bit - set a bit in the xbitmap
* @xb: the xbitmap tree used to record the bit
@@ -70,6 +77,28 @@ int xb_set_bit(struct xb *xb, unsigned long bit)
EXPORT_SYMBOL(xb_set_bit);
/**
+ * xb_preload_and_set_bit - preload the memory and set a bit in the xbitmap
+ * @xb: the xbitmap tree used to record the bit
+ * @bit: index of the bit to set
+ *
+ * A wrapper of the xb_preload() and xb_set_bit().
+ * Returns: 0 on success; -EAGAIN or -ENOMEM on error.
+ */
+int xb_preload_and_set_bit(struct xb *xb, unsigned long bit, gfp_t gfp)
+{
+ int ret = 0;
+
+ if (!xb_preload(gfp))
+ return -ENOMEM;
+
+ ret = xb_set_bit(xb, bit);
+ xb_preload_end();
+
+ return ret;
+}
+EXPORT_SYMBOL(xb_preload_and_set_bit);
+
+/**
* xb_clear_bit - clear a bit in the xbitmap
* @xb: the xbitmap tree used to record the bit
* @bit: index of the bit to clear
@@ -115,6 +144,63 @@ void xb_clear_bit(struct xb *xb, unsigned long bit)
EXPORT_SYMBOL(xb_clear_bit);
/**
+ * xb_clear_bit_range - clear a range of bits in the xbitmap
+ * @start: the start of the bit range, inclusive
+ * @end: the end of the bit range, exclusive
+ *
+ * This function is used to clear a bit in the xbitmap. If all the bits of the
+ * bitmap are 0, the bitmap will be freed.
+ */
+void xb_clear_bit_range(struct xb *xb, unsigned long start, unsigned long end)
+{
+ struct radix_tree_root *root = &xb->xbrt;
+ struct radix_tree_node *node;
+ void **slot;
+ struct ida_bitmap *bitmap;
+ unsigned int nbits;
+
+ for (; start < end; start = (start | (IDA_BITMAP_BITS - 1)) + 1) {
+ unsigned long index = start / IDA_BITMAP_BITS;
+ unsigned long bit = start % IDA_BITMAP_BITS;
+
+ bitmap = __radix_tree_lookup(root, index, &node, &slot);
+ if (radix_tree_exception(bitmap)) {
+ unsigned long ebit = bit + 2;
+ unsigned long tmp = (unsigned long)bitmap;
+
+ nbits = min(end - start + 1, BITS_PER_LONG - ebit);
+
+ if (ebit >= BITS_PER_LONG)
+ continue;
+ bitmap_clear(&tmp, ebit, nbits);
+ if (tmp == RADIX_TREE_EXCEPTIONAL_ENTRY)
+ __radix_tree_delete(root, node, slot);
+ else
+ rcu_assign_pointer(*slot, (void *)tmp);
+ } else if (bitmap) {
+ nbits = min(end - start + 1, IDA_BITMAP_BITS - bit);
+
+ if (nbits != IDA_BITMAP_BITS)
+ bitmap_clear(bitmap->bitmap, bit, nbits);
+
+ if (nbits == IDA_BITMAP_BITS ||
+ bitmap_empty(bitmap->bitmap, IDA_BITMAP_BITS)) {
+ kfree(bitmap);
+ __radix_tree_delete(root, node, slot);
+ }
+ }
+
+ /*
+ * Already reached the last usable ida bitmap, so just return,
+ * otherwise overflow will happen.
+ */
+ if (index == ULONG_MAX / IDA_BITMAP_BITS)
+ break;
+ }
+}
+EXPORT_SYMBOL(xb_clear_bit_range);
+
+/**
* xb_test_bit - test a bit in the xbitmap
* @xb: the xbitmap tree used to record the bit
* @bit: index of the bit to test
@@ -143,6 +229,87 @@ bool xb_test_bit(const struct xb *xb, unsigned long bit)
}
EXPORT_SYMBOL(xb_test_bit);
+static unsigned long xb_find_next_bit(struct xb *xb, unsigned long start,
+ unsigned long end, bool set)
+{
+ struct radix_tree_root *root = &xb->xbrt;
+ struct radix_tree_node *node;
+ void **slot;
+ struct ida_bitmap *bmap;
+ unsigned long ret = end;
+
+ for (; start < end; start = (start | (IDA_BITMAP_BITS - 1)) + 1) {
+ unsigned long index = start / IDA_BITMAP_BITS;
+ unsigned long bit = start % IDA_BITMAP_BITS;
+
+ bmap = __radix_tree_lookup(root, index, &node, &slot);
+ if (radix_tree_exception(bmap)) {
+ unsigned long tmp = (unsigned long)bmap;
+ unsigned long ebit = bit + 2;
+
+ if (ebit >= BITS_PER_LONG)
+ continue;
+ if (set)
+ ret = find_next_bit(&tmp, BITS_PER_LONG, ebit);
+ else
+ ret = find_next_zero_bit(&tmp, BITS_PER_LONG,
+ ebit);
+ if (ret < BITS_PER_LONG)
+ return ret - 2 + IDA_BITMAP_BITS * index;
+ } else if (bmap) {
+ if (set)
+ ret = find_next_bit(bmap->bitmap,
+ IDA_BITMAP_BITS, bit);
+ else
+ ret = find_next_zero_bit(bmap->bitmap,
+ IDA_BITMAP_BITS, bit);
+ if (ret < IDA_BITMAP_BITS)
+ return ret + index * IDA_BITMAP_BITS;
+ } else if (!bmap && !set) {
+ return start;
+ }
+
+ /*
+ * Already reached the last searchable ida bitmap. Return
+ * ULONG_MAX, otherwise overflow will happen.
+ */
+ if (index == ULONG_MAX / IDA_BITMAP_BITS)
+ return ULONG_MAX;
+ }
+
+ return ret;
+}
+
+/**
+ * xb_find_next_set_bit - find the next set bit in a range
+ * @xb: the xbitmap to search
+ * @start: the start of the range, inclusive
+ * @end: the end of the range, exclusive
+ *
+ * Returns: the index of the found bit, or @end + 1 if no such bit is found.
+ */
+unsigned long xb_find_next_set_bit(struct xb *xb, unsigned long start,
+ unsigned long end)
+{
+ return xb_find_next_bit(xb, start, end, 1);
+}
+EXPORT_SYMBOL(xb_find_next_set_bit);
+
+/**
+ * xb_find_next_zero_bit - find the next zero bit in a range
+ * @xb: the xbitmap to search
+ * @start: the start of the range, inclusive
+ * @end: the end of the range, exclusive
+ *
+ * Returns: the index of the found bit, or @end + 1 if no such bit is found.
+ */
+unsigned long xb_find_next_zero_bit(struct xb *xb, unsigned long start,
+ unsigned long end)
+{
+ return xb_find_next_bit(xb, start, end, 0);
+}
+EXPORT_SYMBOL(xb_find_next_zero_bit);
+
#ifndef __KERNEL__
static DEFINE_XB(xb1);
@@ -160,6 +327,66 @@ void xbitmap_check_bit(unsigned long bit)
xb_preload_end();
}
+static void xbitmap_check_bit_range(void)
+{
+ /*
+ * Regular tests
+ * ebit tests: set 1030, 1031, 1034, 1035
+ * Next 1 in [0, 10000) --> 1030
+ * Next 1 in [1030, 1034) --> 1030
+ * Next 1 in [1032, 1034) --> none (1034)
+ * Next 0 in [1030, 1032) --> none (1032)
+ * Next 0 in [1030, 1033) --> 1032
+ *
+ * ida bitmap tests: set 8260, 8261, 8264, 8265
+ * Next 1 in [2000, 10000) --> 8260
+ * Next 1 in [8260, 8264) --> 8260
+ * Next 1 in [8262, 8264) --> none (8264)
+ * Next 0 in [8260, 8262) --> none (8262)
+ * Next 0 in [8260, 8263) --> 8262
+ */
+ assert(!xb_preload_and_set_bit(&xb1, 1030, GFP_KERNEL));
+ assert(!xb_preload_and_set_bit(&xb1, 1031, GFP_KERNEL));
+ assert(!xb_preload_and_set_bit(&xb1, 1034, GFP_KERNEL));
+ assert(!xb_preload_and_set_bit(&xb1, 1035, GFP_KERNEL));
+ assert(!xb_preload_and_set_bit(&xb1, 8260, GFP_KERNEL));
+ assert(!xb_preload_and_set_bit(&xb1, 8261, GFP_KERNEL));
+ assert(!xb_preload_and_set_bit(&xb1, 8264, GFP_KERNEL));
+ assert(!xb_preload_and_set_bit(&xb1, 8265, GFP_KERNEL));
+
+ assert(xb_find_next_set_bit(&xb1, 0, 10000) == 1030);
+ assert(xb_find_next_set_bit(&xb1, 1030, 1034) == 1030);
+ assert(xb_find_next_set_bit(&xb1, 1032, 1034) == 1034);
+ assert(xb_find_next_zero_bit(&xb1, 1030, 1032) == 1032);
+ assert(xb_find_next_zero_bit(&xb1, 1030, 1033) == 1032);
+
+ assert(xb_find_next_set_bit(&xb1, 2000, 10000) == 8260);
+ assert(xb_find_next_set_bit(&xb1, 8260, 8264) == 8260);
+ assert(xb_find_next_set_bit(&xb1, 8262, 8264) == 8264);
+ assert(xb_find_next_zero_bit(&xb1, 8260, 8262) == 8262);
+ assert(xb_find_next_zero_bit(&xb1, 8260, 8263) == 8262);
+
+ xb_clear_bit_range(&xb1, 0, 10000);
+ assert(xb_find_next_set_bit(&xb1, 0, 10000) == 10000);
+
+ /*
+ * Overflow tests:
+ * Next 1 in [0, ULONG_MAX) --> none (ULONG_MAX)
+ * Set ULONG_MAX - 4
+ * Next 1 in [0, ULONG_MAX) --> ULONG_MAX - 4
+ * Next 1 in [ULONG_MAX - 3, ULONG_MAX) --> none (ULONG_MAX)
+ * Next 0 in [ULONG_MAX - 4, ULONG_MAX) --> ULONG_MAX - 3
+ */
+ assert(!xb_preload_and_set_bit(&xb1, ULONG_MAX - 4, GFP_KERNEL));
+ assert(xb_find_next_set_bit(&xb1, ULONG_MAX - 10, ULONG_MAX) ==
+ ULONG_MAX - 4);
+ assert(xb_find_next_set_bit(&xb1, ULONG_MAX - 3, ULONG_MAX) ==
+ ULONG_MAX);
+ assert(xb_find_next_zero_bit(&xb1, ULONG_MAX - 4, ULONG_MAX) ==
+ ULONG_MAX - 3);
+ xb_clear_bit_range(&xb1, ULONG_MAX - 10, ULONG_MAX);
+}
+
void xbitmap_checks(void)
{
xb_init(&xb1);
@@ -171,6 +398,8 @@ void xbitmap_checks(void)
xbitmap_check_bit(1025);
xbitmap_check_bit((1UL << 63) | (1UL << 24));
xbitmap_check_bit((1UL << 63) | (1UL << 24) | 70);
+
+ xbitmap_check_bit_range();
}
int __weak main(void)
diff --git a/tools/include/linux/bitmap.h b/tools/include/linux/bitmap.h
index ca16027..8d0bc1b 100644
--- a/tools/include/linux/bitmap.h
+++ b/tools/include/linux/bitmap.h
@@ -37,6 +37,40 @@ static inline void bitmap_zero(unsigned long *dst, int nbits)
}
}
+static inline void __bitmap_clear(unsigned long *map, unsigned int start,
+ int len)
+{
+ unsigned long *p = map + BIT_WORD(start);
+ const unsigned int size = start + len;
+ int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
+ unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
+
+ while (len - bits_to_clear >= 0) {
+ *p &= ~mask_to_clear;
+ len -= bits_to_clear;
+ bits_to_clear = BITS_PER_LONG;
+ mask_to_clear = ~0UL;
+ p++;
+ }
+ if (len) {
+ mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
+ *p &= ~mask_to_clear;
+ }
+}
+
+static inline __always_inline void bitmap_clear(unsigned long *map,
+ unsigned int start,
+ unsigned int nbits)
+{
+ if (__builtin_constant_p(nbits) && nbits == 1)
+ __clear_bit(start, map);
+ else if (__builtin_constant_p(start & 7) && IS_ALIGNED(start, 8) &&
+ __builtin_constant_p(nbits & 7) && IS_ALIGNED(nbits, 8))
+ memset((char *)map + start / 8, 0, nbits / 8);
+ else
+ __bitmap_clear(map, start, nbits);
+}
+
static inline void bitmap_fill(unsigned long *dst, unsigned int nbits)
{
unsigned int nlongs = BITS_TO_LONGS(nbits);
diff --git a/tools/include/linux/kernel.h b/tools/include/linux/kernel.h
index 0ad8844..3c992ae 100644
--- a/tools/include/linux/kernel.h
+++ b/tools/include/linux/kernel.h
@@ -13,6 +13,8 @@
#define UINT_MAX (~0U)
#endif
+#define IS_ALIGNED(x, a) (((x) & ((typeof(x))(a) - 1)) == 0)
+
#define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
#define PERF_ALIGN(x, a) __PERF_ALIGN_MASK(x, (typeof(x))(a)-1)
--
2.7.4
^ permalink raw reply related
* [PATCH v19 2/7] xbitmap: potential improvement
From: Wei Wang @ 2017-12-12 11:55 UTC (permalink / raw)
To: virtio-dev, linux-kernel, qemu-devel, virtualization, kvm,
linux-mm, mst, mhocko, akpm, mawilcox
Cc: aarcange, yang.zhang.wz, riel, penguin-kernel, liliang.opensource,
willy, amit.shah, quan.xu, cornelia.huck, pbonzini, nilal,
mgorman
In-Reply-To: <1513079759-14169-1-git-send-email-wei.w.wang@intel.com>
This patch made some changes to the original xbitmap implementation from
the linux-dax tree:
- remove xb_fill() and xb_zero() from xbitmap.h since they are not
implemented;
- xb_test_bit: changed "ebit > BITS_PER_LONG" to "ebit >= BITS_PER_LONG",
because bit 64 beyonds the "unsigned long" exceptional entry (0 to 63);
- xb_set_bit: delete the new inserted radix_tree_node when failing to
get the per cpu ida bitmap, this avoids the kind of memory leak of the
unused radix tree node left in the tree.
- xb_clear_bit: change it to be a void function, since the original
implementation reurns nothing than a 0.
- remove the comment above "#define XB_INDEX_BITS", because it causes
confusion based on the feedbacks from the previous discussion;
- xb_preload: with the original implementation, the CPU that successfully
do __radix_tree_preload() may get into sleep by kmalloc(), which has a
risk of getting the caller of xb_preload() scheduled to another CPU
after waken up, and the new CPU may not have radix_tree_node
pre-allocated there, this will be a problem when inserting a node to
the tree later. This patch moves __radix_tree_preload() after kmalloc()
and returns a boolean to indicate the success or failure. Also, add the
__must_check annotation to xb_preload for prudence purpose.
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
include/linux/xbitmap.h | 5 +----
lib/radix-tree.c | 27 +++++++++++++++++++++------
lib/xbitmap.c | 24 +++++++++++++-----------
3 files changed, 35 insertions(+), 21 deletions(-)
diff --git a/include/linux/xbitmap.h b/include/linux/xbitmap.h
index ed75d87..b4d8375 100644
--- a/include/linux/xbitmap.h
+++ b/include/linux/xbitmap.h
@@ -36,15 +36,12 @@ int xb_set_bit(struct xb *xb, unsigned long bit);
bool xb_test_bit(const struct xb *xb, unsigned long bit);
int xb_clear_bit(struct xb *xb, unsigned long bit);
-int xb_zero(struct xb *xb, unsigned long start, unsigned long nbits);
-int xb_fill(struct xb *xb, unsigned long start, unsigned long nbits);
-
static inline bool xb_empty(const struct xb *xb)
{
return radix_tree_empty(&xb->xbrt);
}
-void xb_preload(gfp_t);
+bool xb_preload(gfp_t);
static inline void xb_preload_end(void)
{
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 7000ad6..a039588 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -77,9 +77,6 @@ static struct kmem_cache *radix_tree_node_cachep;
RADIX_TREE_MAP_SHIFT))
#define IDA_PRELOAD_SIZE (IDA_MAX_PATH * 2 - 1)
-/*
- * The XB can go up to unsigned long, but also uses a bitmap.
- */
#define XB_INDEX_BITS (BITS_PER_LONG - ilog2(IDA_BITMAP_BITS))
#define XB_MAX_PATH (DIV_ROUND_UP(XB_INDEX_BITS, \
RADIX_TREE_MAP_SHIFT))
@@ -2145,17 +2142,35 @@ int ida_pre_get(struct ida *ida, gfp_t gfp)
}
EXPORT_SYMBOL(ida_pre_get);
-void xb_preload(gfp_t gfp)
+/**
+ * xb_preload - preload for xb_set_bit()
+ * @gfp_mask: allocation mask to use for preloading
+ *
+ * Preallocate memory to use for the next call to xb_set_bit(). On success,
+ * return true, with preemption disabled. On error, return false with
+ * preemption not disabled.
+ */
+__must_check bool xb_preload(gfp_t gfp)
{
- __radix_tree_preload(gfp, XB_PRELOAD_SIZE);
if (!this_cpu_read(ida_bitmap)) {
struct ida_bitmap *bitmap = kmalloc(sizeof(*bitmap), gfp);
if (!bitmap)
- return;
+ return false;
+ /*
+ * The per-CPU variable is updated with preemption enabled.
+ * If the calling task is unlucky to be scheduled to another
+ * CPU which has no ida_bitmap allocation, it will be detected
+ * when setting a bit (i.e. __xb_set_bit()).
+ */
bitmap = this_cpu_cmpxchg(ida_bitmap, NULL, bitmap);
kfree(bitmap);
}
+
+ if (__radix_tree_preload(gfp, XB_PRELOAD_SIZE) < 0)
+ return false;
+
+ return true;
}
EXPORT_SYMBOL(xb_preload);
diff --git a/lib/xbitmap.c b/lib/xbitmap.c
index 2b547a73..182aa29 100644
--- a/lib/xbitmap.c
+++ b/lib/xbitmap.c
@@ -39,8 +39,10 @@ int xb_set_bit(struct xb *xb, unsigned long bit)
return 0;
}
bitmap = this_cpu_xchg(ida_bitmap, NULL);
- if (!bitmap)
+ if (!bitmap) {
+ __radix_tree_delete(root, node, slot);
return -EAGAIN;
+ }
memset(bitmap, 0, sizeof(*bitmap));
bitmap->bitmap[0] = tmp >> RADIX_TREE_EXCEPTIONAL_SHIFT;
rcu_assign_pointer(*slot, bitmap);
@@ -54,8 +56,10 @@ int xb_set_bit(struct xb *xb, unsigned long bit)
return 0;
}
bitmap = this_cpu_xchg(ida_bitmap, NULL);
- if (!bitmap)
+ if (!bitmap) {
+ __radix_tree_delete(root, node, slot);
return -EAGAIN;
+ }
memset(bitmap, 0, sizeof(*bitmap));
__radix_tree_replace(root, node, slot, bitmap, NULL);
}
@@ -73,7 +77,7 @@ EXPORT_SYMBOL(xb_set_bit);
* This function is used to clear a bit in the xbitmap. If all the bits of the
* bitmap are 0, the bitmap will be freed.
*/
-int xb_clear_bit(struct xb *xb, unsigned long bit)
+void xb_clear_bit(struct xb *xb, unsigned long bit)
{
unsigned long index = bit / IDA_BITMAP_BITS;
struct radix_tree_root *root = &xb->xbrt;
@@ -90,25 +94,23 @@ int xb_clear_bit(struct xb *xb, unsigned long bit)
unsigned long tmp = (unsigned long)bitmap;
if (ebit >= BITS_PER_LONG)
- return 0;
+ return;
tmp &= ~(1UL << ebit);
if (tmp == RADIX_TREE_EXCEPTIONAL_ENTRY)
__radix_tree_delete(root, node, slot);
else
rcu_assign_pointer(*slot, (void *)tmp);
- return 0;
+ return;
}
if (!bitmap)
- return 0;
+ return;
__clear_bit(bit, bitmap->bitmap);
if (bitmap_empty(bitmap->bitmap, IDA_BITMAP_BITS)) {
kfree(bitmap);
__radix_tree_delete(root, node, slot);
}
-
- return 0;
}
EXPORT_SYMBOL(xb_clear_bit);
@@ -133,7 +135,7 @@ bool xb_test_bit(const struct xb *xb, unsigned long bit)
return false;
if (radix_tree_exception(bitmap)) {
bit += RADIX_TREE_EXCEPTIONAL_SHIFT;
- if (bit > BITS_PER_LONG)
+ if (bit >= BITS_PER_LONG)
return false;
return (unsigned long)bitmap & (1UL << bit);
}
@@ -151,9 +153,9 @@ void xbitmap_check_bit(unsigned long bit)
assert(!xb_test_bit(&xb1, bit));
assert(xb_set_bit(&xb1, bit) == 0);
assert(xb_test_bit(&xb1, bit));
- assert(xb_clear_bit(&xb1, bit) == 0);
+ xb_clear_bit(&xb1, bit);
assert(xb_empty(&xb1));
- assert(xb_clear_bit(&xb1, bit) == 0);
+ xb_clear_bit(&xb1, bit);
assert(xb_empty(&xb1));
xb_preload_end();
}
--
2.7.4
^ permalink raw reply related
* [PATCH v19 1/7] xbitmap: Introduce xbitmap
From: Wei Wang @ 2017-12-12 11:55 UTC (permalink / raw)
To: virtio-dev, linux-kernel, qemu-devel, virtualization, kvm,
linux-mm, mst, mhocko, akpm, mawilcox
Cc: aarcange, yang.zhang.wz, riel, penguin-kernel, liliang.opensource,
willy, amit.shah, quan.xu, cornelia.huck, pbonzini, nilal,
mgorman
In-Reply-To: <1513079759-14169-1-git-send-email-wei.w.wang@intel.com>
From: Matthew Wilcox <mawilcox@microsoft.com>
The eXtensible Bitmap is a sparse bitmap representation which is
efficient for set bits which tend to cluster. It supports up to
'unsigned long' worth of bits, and this commit adds the bare bones --
xb_set_bit(), xb_clear_bit() and xb_test_bit().
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
include/linux/radix-tree.h | 2 +
include/linux/xbitmap.h | 52 +++++++++
lib/Makefile | 2 +-
lib/radix-tree.c | 26 ++++-
lib/xbitmap.c | 179 +++++++++++++++++++++++++++++++
tools/testing/radix-tree/Makefile | 12 ++-
tools/testing/radix-tree/linux/xbitmap.h | 1 +
tools/testing/radix-tree/main.c | 4 +
tools/testing/radix-tree/test.h | 1 +
9 files changed, 275 insertions(+), 4 deletions(-)
create mode 100644 include/linux/xbitmap.h
create mode 100644 lib/xbitmap.c
create mode 100644 tools/testing/radix-tree/linux/xbitmap.h
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 23a9c89..fe44f4b 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -315,6 +315,8 @@ void radix_tree_iter_delete(struct radix_tree_root *,
struct radix_tree_iter *iter, void __rcu **slot);
void *radix_tree_delete_item(struct radix_tree_root *, unsigned long, void *);
void *radix_tree_delete(struct radix_tree_root *, unsigned long);
+bool __radix_tree_delete(struct radix_tree_root *r, struct radix_tree_node *n,
+ void **slot);
void radix_tree_clear_tags(struct radix_tree_root *, struct radix_tree_node *,
void __rcu **slot);
unsigned int radix_tree_gang_lookup(const struct radix_tree_root *,
diff --git a/include/linux/xbitmap.h b/include/linux/xbitmap.h
new file mode 100644
index 0000000..ed75d87
--- /dev/null
+++ b/include/linux/xbitmap.h
@@ -0,0 +1,52 @@
+/*
+ * eXtensible Bitmaps
+ * Copyright (c) 2017 Microsoft Corporation <mawilcox@microsoft.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * eXtensible Bitmaps provide an unlimited-size sparse bitmap facility.
+ * All bits are initially zero.
+ */
+
+#include <linux/idr.h>
+
+struct xb {
+ struct radix_tree_root xbrt;
+};
+
+#define XB_INIT { \
+ .xbrt = RADIX_TREE_INIT(IDR_RT_MARKER | GFP_NOWAIT), \
+}
+#define DEFINE_XB(name) struct xb name = XB_INIT
+
+static inline void xb_init(struct xb *xb)
+{
+ INIT_RADIX_TREE(&xb->xbrt, IDR_RT_MARKER | GFP_NOWAIT);
+}
+
+int xb_set_bit(struct xb *xb, unsigned long bit);
+bool xb_test_bit(const struct xb *xb, unsigned long bit);
+int xb_clear_bit(struct xb *xb, unsigned long bit);
+
+int xb_zero(struct xb *xb, unsigned long start, unsigned long nbits);
+int xb_fill(struct xb *xb, unsigned long start, unsigned long nbits);
+
+static inline bool xb_empty(const struct xb *xb)
+{
+ return radix_tree_empty(&xb->xbrt);
+}
+
+void xb_preload(gfp_t);
+
+static inline void xb_preload_end(void)
+{
+ preempt_enable();
+}
diff --git a/lib/Makefile b/lib/Makefile
index d11c48e..08a8183 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -19,7 +19,7 @@ KCOV_INSTRUMENT_dynamic_debug.o := n
lib-y := ctype.o string.o vsprintf.o cmdline.o \
rbtree.o radix-tree.o dump_stack.o timerqueue.o\
- idr.o int_sqrt.o extable.o \
+ idr.o xbitmap.o int_sqrt.o extable.o \
sha1.o chacha20.o irq_regs.o argv_split.o \
flex_proportions.o ratelimit.o show_mem.o \
is_single_threaded.o plist.o decompress.o kobject_uevent.o \
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index c8d5556..7000ad6 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -78,6 +78,14 @@ static struct kmem_cache *radix_tree_node_cachep;
#define IDA_PRELOAD_SIZE (IDA_MAX_PATH * 2 - 1)
/*
+ * The XB can go up to unsigned long, but also uses a bitmap.
+ */
+#define XB_INDEX_BITS (BITS_PER_LONG - ilog2(IDA_BITMAP_BITS))
+#define XB_MAX_PATH (DIV_ROUND_UP(XB_INDEX_BITS, \
+ RADIX_TREE_MAP_SHIFT))
+#define XB_PRELOAD_SIZE (XB_MAX_PATH * 2 - 1)
+
+/*
* Per-cpu pool of preloaded nodes
*/
struct radix_tree_preload {
@@ -839,6 +847,8 @@ int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
offset, 0, 0);
if (!child)
return -ENOMEM;
+ if (is_idr(root))
+ all_tag_set(child, IDR_FREE);
rcu_assign_pointer(*slot, node_to_entry(child));
if (node)
node->count++;
@@ -1982,7 +1992,7 @@ void __radix_tree_delete_node(struct radix_tree_root *root,
delete_node(root, node, update_node);
}
-static bool __radix_tree_delete(struct radix_tree_root *root,
+bool __radix_tree_delete(struct radix_tree_root *root,
struct radix_tree_node *node, void __rcu **slot)
{
void *old = rcu_dereference_raw(*slot);
@@ -2135,6 +2145,20 @@ int ida_pre_get(struct ida *ida, gfp_t gfp)
}
EXPORT_SYMBOL(ida_pre_get);
+void xb_preload(gfp_t gfp)
+{
+ __radix_tree_preload(gfp, XB_PRELOAD_SIZE);
+ if (!this_cpu_read(ida_bitmap)) {
+ struct ida_bitmap *bitmap = kmalloc(sizeof(*bitmap), gfp);
+
+ if (!bitmap)
+ return;
+ bitmap = this_cpu_cmpxchg(ida_bitmap, NULL, bitmap);
+ kfree(bitmap);
+ }
+}
+EXPORT_SYMBOL(xb_preload);
+
void __rcu **idr_get_free_cmn(struct radix_tree_root *root,
struct radix_tree_iter *iter, gfp_t gfp,
unsigned long max)
diff --git a/lib/xbitmap.c b/lib/xbitmap.c
new file mode 100644
index 0000000..2b547a73
--- /dev/null
+++ b/lib/xbitmap.c
@@ -0,0 +1,179 @@
+#include <linux/export.h>
+#include <linux/xbitmap.h>
+#include <linux/bitmap.h>
+#include <linux/slab.h>
+
+/**
+ * xb_set_bit - set a bit in the xbitmap
+ * @xb: the xbitmap tree used to record the bit
+ * @bit: index of the bit to set
+ *
+ * This function is used to set a bit in the xbitmap. If the bitmap that @bit
+ * resides in is not there, the per-cpu ida_bitmap will be taken.
+ *
+ * Returns: 0 on success. %-EAGAIN indicates that @bit was not set.
+ */
+int xb_set_bit(struct xb *xb, unsigned long bit)
+{
+ int err;
+ unsigned long index = bit / IDA_BITMAP_BITS;
+ struct radix_tree_root *root = &xb->xbrt;
+ struct radix_tree_node *node;
+ void **slot;
+ struct ida_bitmap *bitmap;
+ unsigned long ebit;
+
+ bit %= IDA_BITMAP_BITS;
+ ebit = bit + 2;
+
+ err = __radix_tree_create(root, index, 0, &node, &slot);
+ if (err)
+ return err;
+ bitmap = rcu_dereference_raw(*slot);
+ if (radix_tree_exception(bitmap)) {
+ unsigned long tmp = (unsigned long)bitmap;
+
+ if (ebit < BITS_PER_LONG) {
+ tmp |= 1UL << ebit;
+ rcu_assign_pointer(*slot, (void *)tmp);
+ return 0;
+ }
+ bitmap = this_cpu_xchg(ida_bitmap, NULL);
+ if (!bitmap)
+ return -EAGAIN;
+ memset(bitmap, 0, sizeof(*bitmap));
+ bitmap->bitmap[0] = tmp >> RADIX_TREE_EXCEPTIONAL_SHIFT;
+ rcu_assign_pointer(*slot, bitmap);
+ }
+
+ if (!bitmap) {
+ if (ebit < BITS_PER_LONG) {
+ bitmap = (void *)((1UL << ebit) |
+ RADIX_TREE_EXCEPTIONAL_ENTRY);
+ __radix_tree_replace(root, node, slot, bitmap, NULL);
+ return 0;
+ }
+ bitmap = this_cpu_xchg(ida_bitmap, NULL);
+ if (!bitmap)
+ return -EAGAIN;
+ memset(bitmap, 0, sizeof(*bitmap));
+ __radix_tree_replace(root, node, slot, bitmap, NULL);
+ }
+
+ __set_bit(bit, bitmap->bitmap);
+ return 0;
+}
+EXPORT_SYMBOL(xb_set_bit);
+
+/**
+ * xb_clear_bit - clear a bit in the xbitmap
+ * @xb: the xbitmap tree used to record the bit
+ * @bit: index of the bit to clear
+ *
+ * This function is used to clear a bit in the xbitmap. If all the bits of the
+ * bitmap are 0, the bitmap will be freed.
+ */
+int xb_clear_bit(struct xb *xb, unsigned long bit)
+{
+ unsigned long index = bit / IDA_BITMAP_BITS;
+ struct radix_tree_root *root = &xb->xbrt;
+ struct radix_tree_node *node;
+ void **slot;
+ struct ida_bitmap *bitmap;
+ unsigned long ebit;
+
+ bit %= IDA_BITMAP_BITS;
+ ebit = bit + 2;
+
+ bitmap = __radix_tree_lookup(root, index, &node, &slot);
+ if (radix_tree_exception(bitmap)) {
+ unsigned long tmp = (unsigned long)bitmap;
+
+ if (ebit >= BITS_PER_LONG)
+ return 0;
+ tmp &= ~(1UL << ebit);
+ if (tmp == RADIX_TREE_EXCEPTIONAL_ENTRY)
+ __radix_tree_delete(root, node, slot);
+ else
+ rcu_assign_pointer(*slot, (void *)tmp);
+ return 0;
+ }
+
+ if (!bitmap)
+ return 0;
+
+ __clear_bit(bit, bitmap->bitmap);
+ if (bitmap_empty(bitmap->bitmap, IDA_BITMAP_BITS)) {
+ kfree(bitmap);
+ __radix_tree_delete(root, node, slot);
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL(xb_clear_bit);
+
+/**
+ * xb_test_bit - test a bit in the xbitmap
+ * @xb: the xbitmap tree used to record the bit
+ * @bit: index of the bit to test
+ *
+ * This function is used to test a bit in the xbitmap.
+ *
+ * Returns: true if the bit is set, or false otherwise.
+ */
+bool xb_test_bit(const struct xb *xb, unsigned long bit)
+{
+ unsigned long index = bit / IDA_BITMAP_BITS;
+ const struct radix_tree_root *root = &xb->xbrt;
+ struct ida_bitmap *bitmap = radix_tree_lookup(root, index);
+
+ bit %= IDA_BITMAP_BITS;
+
+ if (!bitmap)
+ return false;
+ if (radix_tree_exception(bitmap)) {
+ bit += RADIX_TREE_EXCEPTIONAL_SHIFT;
+ if (bit > BITS_PER_LONG)
+ return false;
+ return (unsigned long)bitmap & (1UL << bit);
+ }
+ return test_bit(bit, bitmap->bitmap);
+}
+EXPORT_SYMBOL(xb_test_bit);
+
+#ifndef __KERNEL__
+
+static DEFINE_XB(xb1);
+
+void xbitmap_check_bit(unsigned long bit)
+{
+ xb_preload(GFP_KERNEL);
+ assert(!xb_test_bit(&xb1, bit));
+ assert(xb_set_bit(&xb1, bit) == 0);
+ assert(xb_test_bit(&xb1, bit));
+ assert(xb_clear_bit(&xb1, bit) == 0);
+ assert(xb_empty(&xb1));
+ assert(xb_clear_bit(&xb1, bit) == 0);
+ assert(xb_empty(&xb1));
+ xb_preload_end();
+}
+
+void xbitmap_checks(void)
+{
+ xb_init(&xb1);
+ xbitmap_check_bit(0);
+ xbitmap_check_bit(30);
+ xbitmap_check_bit(31);
+ xbitmap_check_bit(1023);
+ xbitmap_check_bit(1024);
+ xbitmap_check_bit(1025);
+ xbitmap_check_bit((1UL << 63) | (1UL << 24));
+ xbitmap_check_bit((1UL << 63) | (1UL << 24) | 70);
+}
+
+int __weak main(void)
+{
+ radix_tree_init();
+ xbitmap_checks();
+}
+#endif
diff --git a/tools/testing/radix-tree/Makefile b/tools/testing/radix-tree/Makefile
index fa7ee36..34ece78 100644
--- a/tools/testing/radix-tree/Makefile
+++ b/tools/testing/radix-tree/Makefile
@@ -6,7 +6,8 @@ LDLIBS+= -lpthread -lurcu
TARGETS = main idr-test multiorder
CORE_OFILES := radix-tree.o idr.o linux.o test.o find_bit.o
OFILES = main.o $(CORE_OFILES) regression1.o regression2.o regression3.o \
- tag_check.o multiorder.o idr-test.o iteration_check.o benchmark.o
+ tag_check.o multiorder.o idr-test.o iteration_check.o benchmark.o \
+ xbitmap.o
ifndef SHIFT
SHIFT=3
@@ -25,8 +26,11 @@ idr-test: idr-test.o $(CORE_OFILES)
multiorder: multiorder.o $(CORE_OFILES)
+xbitmap: xbitmap.o $(CORE_OFILES)
+ $(CC) $(CFLAGS) $(LDFLAGS) $^ -o xbitmap
+
clean:
- $(RM) $(TARGETS) *.o radix-tree.c idr.c generated/map-shift.h
+ $(RM) $(TARGETS) *.o radix-tree.c idr.c xbitmap.c generated/map-shift.h
vpath %.c ../../lib
@@ -34,6 +38,7 @@ $(OFILES): Makefile *.h */*.h generated/map-shift.h \
../../include/linux/*.h \
../../include/asm/*.h \
../../../include/linux/radix-tree.h \
+ ../../../include/linux/xbitmap.h \
../../../include/linux/idr.h
radix-tree.c: ../../../lib/radix-tree.c
@@ -42,6 +47,9 @@ radix-tree.c: ../../../lib/radix-tree.c
idr.c: ../../../lib/idr.c
sed -e 's/^static //' -e 's/__always_inline //' -e 's/inline //' < $< > $@
+xbitmap.c: ../../../lib/xbitmap.c
+ sed -e 's/^static //' -e 's/__always_inline //' -e 's/inline //' < $< > $@
+
.PHONY: mapshift
mapshift:
diff --git a/tools/testing/radix-tree/linux/xbitmap.h b/tools/testing/radix-tree/linux/xbitmap.h
new file mode 100644
index 0000000..61de214
--- /dev/null
+++ b/tools/testing/radix-tree/linux/xbitmap.h
@@ -0,0 +1 @@
+#include "../../../../include/linux/xbitmap.h"
diff --git a/tools/testing/radix-tree/main.c b/tools/testing/radix-tree/main.c
index 257f3f8..d112363 100644
--- a/tools/testing/radix-tree/main.c
+++ b/tools/testing/radix-tree/main.c
@@ -326,6 +326,10 @@ static void single_thread_tests(bool long_run)
rcu_barrier();
printv(2, "after idr_checks: %d allocated, preempt %d\n",
nr_allocated, preempt_count);
+ xbitmap_checks();
+ rcu_barrier();
+ printv(2, "after xbitmap_checks: %d allocated, preempt %d\n",
+ nr_allocated, preempt_count);
big_gang_check(long_run);
rcu_barrier();
printv(2, "after big_gang_check: %d allocated, preempt %d\n",
diff --git a/tools/testing/radix-tree/test.h b/tools/testing/radix-tree/test.h
index d9c031d..8175d6b 100644
--- a/tools/testing/radix-tree/test.h
+++ b/tools/testing/radix-tree/test.h
@@ -38,6 +38,7 @@ void benchmark(void);
void idr_checks(void);
void ida_checks(void);
void ida_thread_tests(void);
+void xbitmap_checks(void);
struct item *
item_tag_set(struct radix_tree_root *root, unsigned long index, int tag);
--
2.7.4
^ permalink raw reply related
* [PATCH v19 0/7] Virtio-balloon Enhancement
From: Wei Wang @ 2017-12-12 11:55 UTC (permalink / raw)
To: virtio-dev, linux-kernel, qemu-devel, virtualization, kvm,
linux-mm, mst, mhocko, akpm, mawilcox
Cc: aarcange, yang.zhang.wz, riel, penguin-kernel, liliang.opensource,
willy, amit.shah, quan.xu, cornelia.huck, pbonzini, nilal,
mgorman
This patch series enhances the existing virtio-balloon with the following
new features:
1) fast ballooning: transfer ballooned pages between the guest and host in
chunks using sgs, instead of one array each time; and
2) free page block reporting: a new virtqueue to report guest free pages
to the host.
The second feature can be used to accelerate live migration of VMs. Here
are some details:
Live migration needs to transfer the VM's memory from the source machine
to the destination round by round. For the 1st round, all the VM's memory
is transferred. From the 2nd round, only the pieces of memory that were
written by the guest (after the 1st round) are transferred. One method
that is popularly used by the hypervisor to track which part of memory is
written is to write-protect all the guest memory.
The second feature enables the optimization of the 1st round memory
transfer - the hypervisor can skip the transfer of guest free pages in the
1st round. It is not concerned that the memory pages are used after they
are given to the hypervisor as a hint of the free pages, because they will
be tracked by the hypervisor and transferred in the next round if they are
used and written.
ChangeLog:
v18->v19:
1) patch 3:
- xb_clear_bit_range and xb_find_next_bit will deal with range [start,
end), where end is changed to be exclusive of the range.
- add overflow checks at the end of xb_clear_bit_range and
xb_find_next_bit
- add overflow related test cases
2) patch 4:
- change back to the previous add_one_sg methond, which is based on the
scatterlist struct
- tell_host_sgs: use "uint64_t len" to avoid overflow
- batch_balloon_page_sg: a simpler function to implement the batching of
sgs
3) patch 6: batch_free_page_sg: batch sgs using the previous scatterlist struct
4) patch 7: add a config field, poison_val, to tell the host about the poison
value
v17->v18:
1) patch 1-2: new to solve some tools related compilation issues
2) patch 3: revert to the original xbitmap implementation from Matthew
Wilcox with some minor changes (e.g. comments added to the exported
functions)
3) patch 4: summarize the changes we want to make to patch 3
4) patch 5: add the developer notes as a reminder for users to avoid
concurrent accesses to the ida bitmap
5) patch 6: a new vring API to allow users to directly pass in a physical
address to a vring desc
6) patch 7: ballooning time is reduced from ~490ms to ~440ms with the new
implementation
- use the new API from patch 6 to send balloon pages
- xb_preload with "GFP_NOWAIT | __GFP_NOWARN" flag;
- handle the case when xb_set_page() fails to avoid memory leak;
- put xb_set_page() under the balloon lock
7) patch 9: simper implementation
- start free page reporting by sending a new cmd id from the host
- guest acks the start or stop via adding a cmd id to the free page vq
- use vb->report_free_page, instead of vb->report_free_page_stop
- use WRITE_ONCE/READ_ONCE to access vb->report_free_page
- use the new API from patch 6 to send free pages to avoid the
unnecessary use of kaddr.
8) patch 10: new patch to solve the page posioning issue reported by
Michael S. Tsirkin
v16->v17:
1) patch 1: please check the commit log there;
2) patch 3: included Michael S. Tsirkin patch to fix the potential
deadlock issue;
3) patch 4: use BUG_ON if virtqueue_add_ returns error, which is
expected never to happen;
4) patch 4: add leak_balloon_sg_oom, which is used in the oom case when
VIRTIO_BALLOON_F_SG is in use;
5) patch 6: use config registers, instead of a vq, as the command channel
between the host and guest;
6) patch 6: add the command sequence id support.
v15->v16:
1) mm: stop reporting the free pfn range if the callback returns false;
2) mm: move some implementaion of walk_free_mem_block into a function to
make the code layout looks better;
3) xbitmap: added some optimizations suggested by Matthew, please refer to
the ChangLog in the xbitmap patch for details.
4) xbitmap: added a test suite
5) virtio-balloon: bail out with a warning when virtqueue_add_inbuf returns
an error
6) virtio-balloon: some small code re-arrangement, e.g. detachinf used buf
from the vq before adding a new buf
v14->v15:
1) mm: make the report callback return a bool value - returning 1 to stop
walking through the free page list.
2) virtio-balloon: batching sgs of balloon pages till the vq is full
3) virtio-balloon: create a new workqueue, rather than using the default
system_wq, to queue the free page reporting work item.
4) virtio-balloon: add a ctrl_vq to be a central control plane which will
handle all the future control related commands between the host and guest.
Add free page report as the first feature controlled under ctrl_vq, and
the free_page_vq is a data plane vq dedicated to the transmission of free
page blocks.
v13->v14:
1) xbitmap: move the code from lib/radix-tree.c to lib/xbitmap.c.
2) xbitmap: consolidate the implementation of xb_bit_set/clear/test into
one xb_bit_ops.
3) xbitmap: add documents for the exported APIs.
4) mm: rewrite the function to walk through free page blocks.
5) virtio-balloon: when reporting a free page blcok to the device, if the
vq is full (less likey to happen in practice), just skip reporting this
block, instead of busywaiting till an entry gets released.
6) virtio-balloon: fail the probe function if adding the signal buf in
init_vqs fails.
v12->v13:
1) mm: use a callback function to handle the the free page blocks from the
report function. This avoids exposing the zone internal to a kernel
module.
2) virtio-balloon: send balloon pages or a free page block using a single
sg each time. This has the benefits of simpler implementation with no new
APIs.
3) virtio-balloon: the free_page_vq is used to report free pages only (no
multiple usages interleaving)
4) virtio-balloon: Balloon pages and free page blocks are sent via input
sgs, and the completion signal to the host is sent via an output sg.
v11->v12:
1) xbitmap: use the xbitmap from Matthew Wilcox to record ballooned pages.
2) virtio-ring: enable the driver to build up a desc chain using vring
desc.
3) virtio-ring: Add locking to the existing START_USE() and END_USE()
macro to lock/unlock the vq when a vq operation starts/ends.
4) virtio-ring: add virtqueue_kick_sync() and virtqueue_kick_async()
5) virtio-balloon: describe chunks of ballooned pages and free pages
blocks directly using one or more chains of desc from the vq.
v10->v11:
1) virtio_balloon: use vring_desc to describe a chunk;
2) virtio_ring: support to add an indirect desc table to virtqueue;
3) virtio_balloon: use cmdq to report guest memory statistics.
v9->v10:
1) mm: put report_unused_page_block() under CONFIG_VIRTIO_BALLOON;
2) virtio-balloon: add virtballoon_validate();
3) virtio-balloon: msg format change;
4) virtio-balloon: move miscq handling to a task on system_freezable_wq;
5) virtio-balloon: code cleanup.
v8->v9:
1) Split the two new features, VIRTIO_BALLOON_F_BALLOON_CHUNKS and
VIRTIO_BALLOON_F_MISC_VQ, which were mixed together in the previous
implementation;
2) Simpler function to get the free page block.
v7->v8:
1) Use only one chunk format, instead of two.
2) re-write the virtio-balloon implementation patch.
3) commit changes
4) patch re-org
Matthew Wilcox (1):
xbitmap: Introduce xbitmap
Wei Wang (6):
xbitmap: potential improvement
xbitmap: add more operations
virtio-balloon: VIRTIO_BALLOON_F_SG
mm: support reporting free page blocks
virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_VQ
virtio-balloon: don't report free pages when page poisoning is enabled
drivers/virtio/virtio_balloon.c | 442 +++++++++++++++++++++++++++----
include/linux/mm.h | 6 +
include/linux/radix-tree.h | 2 +
include/linux/xbitmap.h | 55 ++++
include/uapi/linux/virtio_balloon.h | 7 +
lib/Makefile | 2 +-
lib/radix-tree.c | 41 ++-
lib/xbitmap.c | 410 ++++++++++++++++++++++++++++
mm/page_alloc.c | 91 +++++++
tools/include/linux/bitmap.h | 34 +++
tools/include/linux/kernel.h | 2 +
tools/testing/radix-tree/Makefile | 12 +-
tools/testing/radix-tree/linux/xbitmap.h | 1 +
tools/testing/radix-tree/main.c | 4 +
tools/testing/radix-tree/test.h | 1 +
15 files changed, 1056 insertions(+), 54 deletions(-)
create mode 100644 include/linux/xbitmap.h
create mode 100644 lib/xbitmap.c
create mode 100644 tools/testing/radix-tree/linux/xbitmap.h
--
2.7.4
^ permalink raw reply
* Re: [PATCH 3/3] virtio: put reference count of virtio_device.dev
From: Cornelia Huck @ 2017-12-12 10:33 UTC (permalink / raw)
To: weiping zhang; +Cc: virtualization, mst
In-Reply-To: <f761f1f5a032b7233288bc6e6ae45e44867a31bc.1513007310.git.zhangweiping@didichuxing.com>
On Mon, 11 Dec 2017 23:55:38 +0800
weiping zhang <zhangweiping@didichuxing.com> wrote:
> rproc_virtio_dev_release will be called iff virtio_device.dev's
> refer count became to 0. Here we should put vdev.dev, and then
> rproc->dev's cleanup will be done in rproc_virtio_dev_release.
>
> Signed-off-by: weiping zhang <zhangweiping@didichuxing.com>
> ---
> drivers/remoteproc/remoteproc_virtio.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/remoteproc/remoteproc_virtio.c b/drivers/remoteproc/remoteproc_virtio.c
> index 2946348..b0633fd 100644
> --- a/drivers/remoteproc/remoteproc_virtio.c
> +++ b/drivers/remoteproc/remoteproc_virtio.c
> @@ -327,7 +327,7 @@ int rproc_add_virtio_dev(struct rproc_vdev *rvdev, int id)
>
> ret = register_virtio_device(vdev);
> if (ret) {
> - put_device(&rproc->dev);
> + put_device(&vdev->dev);
> dev_err(dev, "failed to register vdev: %d\n", ret);
> goto out;
> }
Uh, rproc_vdev is really weird. It embeds a struct virtio_device, and
in addition a struct kref. At a glance, it seems to be correct, though.
Your change is more obviously sane.
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
^ permalink raw reply
* Re: [PATCH 2/3] virtio: use put_device instead of kfree
From: Cornelia Huck @ 2017-12-12 10:17 UTC (permalink / raw)
To: weiping zhang; +Cc: virtualization, mst
In-Reply-To: <3c3ed58013b0266886e72dc11424e0b93a745e18.1513007310.git.zhangweiping@didichuxing.com>
On Mon, 11 Dec 2017 23:55:26 +0800
weiping zhang <zhangweiping@didichuxing.com> wrote:
> don't free vp_vdev until vp_vdev.dev.release be called.
Same comment as for the virtio_pci patch.
>
> Signed-off-by: weiping zhang <zhangweiping@didichuxing.com>
> ---
> drivers/misc/mic/vop/vop_main.c | 16 +++++++++-------
> 1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/misc/mic/vop/vop_main.c b/drivers/misc/mic/vop/vop_main.c
> index a341938..8c716a0 100644
> --- a/drivers/misc/mic/vop/vop_main.c
> +++ b/drivers/misc/mic/vop/vop_main.c
> @@ -452,10 +452,12 @@ static irqreturn_t vop_virtio_intr_handler(int irq, void *data)
>
> static void vop_virtio_release_dev(struct device *_d)
> {
> - /*
> - * No need for a release method similar to virtio PCI.
> - * Provide an empty one to avoid getting a warning from core.
> - */
> + struct virtio_device *vdev =
> + container_of(_d, struct virtio_device, dev);
> + struct _vop_vdev *vop_vdev =
> + container_of(vdev, struct _vop_vdev, vdev);
> +
> + kfree(vop_vdev);
> }
>
> /*
> @@ -501,7 +503,9 @@ static int _vop_add_device(struct mic_device_desc __iomem *d,
> dev_err(_vop_dev(vdev),
> "Failed to register vop device %u type %u\n",
> offset, type);
> - goto free_irq;
> + vpdev->hw_ops->free_irq(vpdev, vdev->virtio_cookie, vdev);
> + put_device(&vdev->vdev.dev);
> + return ret;
> }
> writeq((u64)vdev, &vdev->dc->vdev);
> dev_dbg(_vop_dev(vdev), "%s: registered vop device %u type %u vdev %p\n",
> @@ -509,8 +513,6 @@ static int _vop_add_device(struct mic_device_desc __iomem *d,
>
> return 0;
>
> -free_irq:
> - vpdev->hw_ops->free_irq(vpdev, vdev->virtio_cookie, vdev);
> kfree:
> kfree(vdev);
> return ret;
BTW, the kfree(vdev) in _vop_remove_device() is also wrong (needs to be
a put_device() as well).
^ permalink raw reply
* Re: [PATCH 1/3] virtio_pci: use put_device instead of kfree
From: Cornelia Huck @ 2017-12-12 10:00 UTC (permalink / raw)
To: weiping zhang; +Cc: virtualization, mst
In-Reply-To: <0657b3e821f7c9f95ecf93e0286fa0b48a3e1289.1513007310.git.zhangweiping@didichuxing.com>
On Mon, 11 Dec 2017 23:55:16 +0800
weiping zhang <zhangweiping@didichuxing.com> wrote:
> don't free vp_dev until vp_dev->vdev.dev.release be called.
Maybe add the same description as in your virtio_mmio patch so that it
is clear why the kfree() is not ok?
>
> Signed-off-by: weiping zhang <zhangweiping@didichuxing.com>
> ---
> drivers/virtio/virtio_pci_common.c | 17 +++++++++--------
> 1 file changed, 9 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
> index 1c4797e..91d20f7 100644
> --- a/drivers/virtio/virtio_pci_common.c
> +++ b/drivers/virtio/virtio_pci_common.c
> @@ -551,16 +551,17 @@ static int virtio_pci_probe(struct pci_dev *pci_dev,
> pci_set_master(pci_dev);
>
> rc = register_virtio_device(&vp_dev->vdev);
> - if (rc)
> - goto err_register;
> + if (rc) {
> + if (vp_dev->ioaddr)
> + virtio_pci_legacy_remove(vp_dev);
> + else
> + virtio_pci_modern_remove(vp_dev);
> + pci_disable_device(pci_dev);
> + put_device(&vp_dev->vdev.dev);
> + }
>
> - return 0;
> + return rc;
>
> -err_register:
> - if (vp_dev->ioaddr)
> - virtio_pci_legacy_remove(vp_dev);
> - else
> - virtio_pci_modern_remove(vp_dev);
> err_probe:
> pci_disable_device(pci_dev);
> err_enable_device:
Otherwise, looks good.
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
^ permalink raw reply
* Re: [PATCH] ptr_ring: add barriers
From: George Cherian @ 2017-12-12 6:28 UTC (permalink / raw)
To: David Miller, mst
Cc: george.cherian, netdev, linux-kernel, virtualization, edumazet
In-Reply-To: <20171211.105308.1899676147655539775.davem@davemloft.net>
Hi David,
On 12/11/2017 09:23 PM, David Miller wrote:
> From: "Michael S. Tsirkin" <mst@redhat.com>
> Date: Tue, 5 Dec 2017 21:29:37 +0200
>
>> Users of ptr_ring expect that it's safe to give the
>> data structure a pointer and have it be available
>> to consumers, but that actually requires an smb_wmb
>> or a stronger barrier.
>>
>> In absence of such barriers and on architectures that reorder writes,
>> consumer might read an un=initialized value from an skb pointer stored
>> in the skb array. This was observed causing crashes.
>>
>> To fix, add memory barriers. The barrier we use is a wmb, the
>> assumption being that producers do not need to read the value so we do
>> not need to order these reads.
>>
>> Reported-by: George Cherian <george.cherian@cavium.com>
>> Suggested-by: Jason Wang <jasowang@redhat.com>
>> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
>
> I'm asked for asking for testing feedback and did not get it in a
> reasonable amount of time.
>
The tests have completed more than 48 hours without any failures.
I won't interrupt the same and run for longer time.
In case of any issue I will report the same.
> So I'm applying this as-is, and queueing it up for -stable.
>
> Thank you.
Regards,
-George
>
^ permalink raw reply
* Re: [PATCH 02/13] fbdev: add remove_conflicting_pci_framebuffers()
From: Sudip Mukherjee @ 2017-12-11 21:57 UTC (permalink / raw)
To: Emil Velikov
Cc: Teddy Wang, David Airlie, Greg KH, amd-gfx mailing list,
Michał Mirosław, ML dri-devel, Daniel Vetter,
Alex Deucher, open list:VIRTIO GPU DRIVER, Christian König
In-Reply-To: <CACvgo52NmpWv4DdwMuu3b9fZx++Wd2zvCvtvN75LxPqmycpCtQ@mail.gmail.com>
Hi Emil,
On Fri, Dec 01, 2017 at 02:40:11PM +0000, Emil Velikov wrote:
> On 30 November 2017 at 23:49, Sudip Mukherjee
> <sudipm.mukherjee@gmail.com> wrote:
> > Hi Daniel,
> >
> > On Wed, Nov 29, 2017 at 10:56:34AM +0100, Daniel Vetter wrote:
<snip>
> > submit it to dri-devel.
> >
> A crazy idea, mostly towards Tedd and Sudip:
>
> Start small and build gradually. An example split for separate patch series:
>
> - one HW, basic setup + atomic KMS
> - add second HW
> - more KMS features
> - fancy memory management
> - 2D/3D/other acceleration
>
> The driver as seen above tries to do all of the above (almost, it's not atomic)
> at once - 40k loc.
>
> Someone familiar with the code can quickly split it up and while doing
> so, feed it through checkpatch.
I can try but will be very tough since I have to go through the code to
get familiar with it and, as mentioned before, its not part of my dayjob,
so time will be a problem. Developing from scratch takes much more time
than fixing something.
> Current code is _very_ far from kernel coding style, plus the
> copyright blurp is very disturbing:
I will fix the coding style before my first submission to dri-devel,
which should be in January after I have setup my desktop with the
hardware for testing.
The copyright thing - I am sure Teddy can talk to his company and will
confirm that we can change it to the way kernel code is done.
--
Regards
Sudip
^ permalink raw reply
* [PATCH 3/3] virtio: put reference count of virtio_device.dev
From: weiping zhang @ 2017-12-11 15:55 UTC (permalink / raw)
To: cohuck, mst, jasowang; +Cc: virtualization
In-Reply-To: <cover.1513007310.git.zhangweiping@didichuxing.com>
rproc_virtio_dev_release will be called iff virtio_device.dev's
refer count became to 0. Here we should put vdev.dev, and then
rproc->dev's cleanup will be done in rproc_virtio_dev_release.
Signed-off-by: weiping zhang <zhangweiping@didichuxing.com>
---
drivers/remoteproc/remoteproc_virtio.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/remoteproc/remoteproc_virtio.c b/drivers/remoteproc/remoteproc_virtio.c
index 2946348..b0633fd 100644
--- a/drivers/remoteproc/remoteproc_virtio.c
+++ b/drivers/remoteproc/remoteproc_virtio.c
@@ -327,7 +327,7 @@ int rproc_add_virtio_dev(struct rproc_vdev *rvdev, int id)
ret = register_virtio_device(vdev);
if (ret) {
- put_device(&rproc->dev);
+ put_device(&vdev->dev);
dev_err(dev, "failed to register vdev: %d\n", ret);
goto out;
}
--
2.9.4
^ permalink raw reply related
* [PATCH 2/3] virtio: use put_device instead of kfree
From: weiping zhang @ 2017-12-11 15:55 UTC (permalink / raw)
To: cohuck, mst, jasowang; +Cc: virtualization
In-Reply-To: <cover.1513007310.git.zhangweiping@didichuxing.com>
don't free vp_vdev until vp_vdev.dev.release be called.
Signed-off-by: weiping zhang <zhangweiping@didichuxing.com>
---
drivers/misc/mic/vop/vop_main.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/drivers/misc/mic/vop/vop_main.c b/drivers/misc/mic/vop/vop_main.c
index a341938..8c716a0 100644
--- a/drivers/misc/mic/vop/vop_main.c
+++ b/drivers/misc/mic/vop/vop_main.c
@@ -452,10 +452,12 @@ static irqreturn_t vop_virtio_intr_handler(int irq, void *data)
static void vop_virtio_release_dev(struct device *_d)
{
- /*
- * No need for a release method similar to virtio PCI.
- * Provide an empty one to avoid getting a warning from core.
- */
+ struct virtio_device *vdev =
+ container_of(_d, struct virtio_device, dev);
+ struct _vop_vdev *vop_vdev =
+ container_of(vdev, struct _vop_vdev, vdev);
+
+ kfree(vop_vdev);
}
/*
@@ -501,7 +503,9 @@ static int _vop_add_device(struct mic_device_desc __iomem *d,
dev_err(_vop_dev(vdev),
"Failed to register vop device %u type %u\n",
offset, type);
- goto free_irq;
+ vpdev->hw_ops->free_irq(vpdev, vdev->virtio_cookie, vdev);
+ put_device(&vdev->vdev.dev);
+ return ret;
}
writeq((u64)vdev, &vdev->dc->vdev);
dev_dbg(_vop_dev(vdev), "%s: registered vop device %u type %u vdev %p\n",
@@ -509,8 +513,6 @@ static int _vop_add_device(struct mic_device_desc __iomem *d,
return 0;
-free_irq:
- vpdev->hw_ops->free_irq(vpdev, vdev->virtio_cookie, vdev);
kfree:
kfree(vdev);
return ret;
--
2.9.4
^ permalink raw reply related
* [PATCH 1/3] virtio_pci: use put_device instead of kfree
From: weiping zhang @ 2017-12-11 15:55 UTC (permalink / raw)
To: cohuck, mst, jasowang; +Cc: virtualization
In-Reply-To: <cover.1513007310.git.zhangweiping@didichuxing.com>
don't free vp_dev until vp_dev->vdev.dev.release be called.
Signed-off-by: weiping zhang <zhangweiping@didichuxing.com>
---
drivers/virtio/virtio_pci_common.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
index 1c4797e..91d20f7 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -551,16 +551,17 @@ static int virtio_pci_probe(struct pci_dev *pci_dev,
pci_set_master(pci_dev);
rc = register_virtio_device(&vp_dev->vdev);
- if (rc)
- goto err_register;
+ if (rc) {
+ if (vp_dev->ioaddr)
+ virtio_pci_legacy_remove(vp_dev);
+ else
+ virtio_pci_modern_remove(vp_dev);
+ pci_disable_device(pci_dev);
+ put_device(&vp_dev->vdev.dev);
+ }
- return 0;
+ return rc;
-err_register:
- if (vp_dev->ioaddr)
- virtio_pci_legacy_remove(vp_dev);
- else
- virtio_pci_modern_remove(vp_dev);
err_probe:
pci_disable_device(pci_dev);
err_enable_device:
--
2.9.4
^ permalink raw reply related
* [PATCH 0/3] fix cleanup for fail to register_virtio_device
From: weiping zhang @ 2017-12-11 15:53 UTC (permalink / raw)
To: cohuck, mst, jasowang; +Cc: virtualization
This series fix the cleanup for the caller of register_virtio_device,
the main work is use put_device instead of kfree.
weiping zhang (3):
virtio_pci: use put_device instead of kfree
virtio: use put_device instead of kfree
virtio: put reference count of virtio_device.dev
drivers/misc/mic/vop/vop_main.c | 16 +++++++++-------
drivers/remoteproc/remoteproc_virtio.c | 2 +-
drivers/virtio/virtio_pci_common.c | 17 +++++++++--------
3 files changed, 19 insertions(+), 16 deletions(-)
--
2.9.4
^ permalink raw reply
* Re: [PATCH] ptr_ring: add barriers
From: David Miller @ 2017-12-11 15:53 UTC (permalink / raw)
To: mst; +Cc: george.cherian, netdev, linux-kernel, virtualization, edumazet
In-Reply-To: <1512501990-30029-1-git-send-email-mst@redhat.com>
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: Tue, 5 Dec 2017 21:29:37 +0200
> Users of ptr_ring expect that it's safe to give the
> data structure a pointer and have it be available
> to consumers, but that actually requires an smb_wmb
> or a stronger barrier.
>
> In absence of such barriers and on architectures that reorder writes,
> consumer might read an un=initialized value from an skb pointer stored
> in the skb array. This was observed causing crashes.
>
> To fix, add memory barriers. The barrier we use is a wmb, the
> assumption being that producers do not need to read the value so we do
> not need to order these reads.
>
> Reported-by: George Cherian <george.cherian@cavium.com>
> Suggested-by: Jason Wang <jasowang@redhat.com>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
I'm asked for asking for testing feedback and did not get it in a
reasonable amount of time.
So I'm applying this as-is, and queueing it up for -stable.
Thank you.
^ permalink raw reply
* Re: [PATCH v18 10/10] virtio-balloon: don't report free pages when page poisoning is enabled
From: Michael S. Tsirkin @ 2017-12-11 13:24 UTC (permalink / raw)
To: Wei Wang
Cc: yang.zhang.wz, kvm, penguin-kernel, liliang.opensource,
qemu-devel, virtualization, linux-mm, aarcange, virtio-dev,
mawilcox, willy, quan.xu, nilal, riel, cornelia.huck, mhocko,
linux-kernel, amit.shah, pbonzini, akpm, mgorman
In-Reply-To: <5A2E27F5.2010703@intel.com>
On Mon, Dec 11, 2017 at 02:38:45PM +0800, Wei Wang wrote:
> On 12/01/2017 11:49 PM, Michael S. Tsirkin wrote:
> > On Wed, Nov 29, 2017 at 09:55:26PM +0800, Wei Wang wrote:
> > > The guest free pages should not be discarded by the live migration thread
> > > when page poisoning is enabled with PAGE_POISONING_NO_SANITY=n, because
> > > skipping the transfer of such poisoned free pages will trigger false
> > > positive when new pages are allocated and checked on the destination.
> > > This patch skips the reporting of free pages in the above case.
> > >
> > > Reported-by: Michael S. Tsirkin <mst@redhat.com>
> > > Signed-off-by: Wei Wang <wei.w.wang@intel.com>
> > > Cc: Michal Hocko <mhocko@suse.com>
> > > ---
> > > drivers/virtio/virtio_balloon.c | 4 +++-
> > > 1 file changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> > > index 035bd3a..6ac4cff 100644
> > > --- a/drivers/virtio/virtio_balloon.c
> > > +++ b/drivers/virtio/virtio_balloon.c
> > > @@ -652,7 +652,9 @@ static void report_free_page(struct work_struct *work)
> > > /* Start by sending the obtained cmd id to the host with an outbuf */
> > > send_one_desc(vb, vb->free_page_vq, virt_to_phys(&vb->start_cmd_id),
> > > sizeof(uint32_t), false, true, false);
> > > - walk_free_mem_block(vb, 0, &virtio_balloon_send_free_pages);
> > > + if (!(page_poisoning_enabled() &&
> > > + !IS_ENABLED(CONFIG_PAGE_POISONING_NO_SANITY)))
> > > + walk_free_mem_block(vb, 0, &virtio_balloon_send_free_pages);
> > > /*
> > > * End by sending the stop id to the host with an outbuf. Use the
> > > * non-batching mode here to trigger a kick after adding the stop id.
> > PAGE_POISONING_ZERO is actually OK.
> >
> > But I really would prefer it that we still send pages to host,
> > otherwise debugging becomes much harder.
> >
> > And it does not have to be completely useless, even though
> > you can not discard them as they would be zero-filled then.
> >
> > How about a config field telling host what should be there in the free
> > pages? This way even though host can not discard them, host can send
> > them out without reading them, still a win.
> >
> >
>
> Since this poison value comes with the free page reporting feature, how
> about sending the poison value via the free_page_vq, along with the cmd id
> in the outbuf? That is, use the following interface:
>
> struct virtio_balloon_free_page_vq_hdr {
> bool page_poisoning;
> __virtio32 poison_value;
> __virtio32 cmd_id;
> }
Can we put the value in config space instead?
> We need "bool page_poisoning" because "poison_value=0" doesn't tell whether
> page poising is in use by the guest.
Can we use a feature bit for this?
> PAGE_POISONING_ZERO sets
> "page_poisoning=true, poisoning_value=0", and the host will send the
> 0-filled pages to the destination (if not sending 0-filled pages, the
> destination host would offer non-zero pages to the guest)
Why would it? Linux zeroes all pages on alloc.
> The host can discard free pages only when "page_poisoning=false".
>
> Best,
> Wei
^ permalink raw reply
* Re: [PATCH v18 10/10] virtio-balloon: don't report free pages when page poisoning is enabled
From: Wei Wang @ 2017-12-11 6:38 UTC (permalink / raw)
To: Michael S. Tsirkin
Cc: yang.zhang.wz, kvm, penguin-kernel, liliang.opensource,
qemu-devel, virtualization, linux-mm, aarcange, virtio-dev,
mawilcox, willy, quan.xu, nilal, riel, cornelia.huck, mhocko,
linux-kernel, amit.shah, pbonzini, akpm, mgorman
In-Reply-To: <20171201173951-mutt-send-email-mst@kernel.org>
On 12/01/2017 11:49 PM, Michael S. Tsirkin wrote:
> On Wed, Nov 29, 2017 at 09:55:26PM +0800, Wei Wang wrote:
>> The guest free pages should not be discarded by the live migration thread
>> when page poisoning is enabled with PAGE_POISONING_NO_SANITY=n, because
>> skipping the transfer of such poisoned free pages will trigger false
>> positive when new pages are allocated and checked on the destination.
>> This patch skips the reporting of free pages in the above case.
>>
>> Reported-by: Michael S. Tsirkin <mst@redhat.com>
>> Signed-off-by: Wei Wang <wei.w.wang@intel.com>
>> Cc: Michal Hocko <mhocko@suse.com>
>> ---
>> drivers/virtio/virtio_balloon.c | 4 +++-
>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
>> index 035bd3a..6ac4cff 100644
>> --- a/drivers/virtio/virtio_balloon.c
>> +++ b/drivers/virtio/virtio_balloon.c
>> @@ -652,7 +652,9 @@ static void report_free_page(struct work_struct *work)
>> /* Start by sending the obtained cmd id to the host with an outbuf */
>> send_one_desc(vb, vb->free_page_vq, virt_to_phys(&vb->start_cmd_id),
>> sizeof(uint32_t), false, true, false);
>> - walk_free_mem_block(vb, 0, &virtio_balloon_send_free_pages);
>> + if (!(page_poisoning_enabled() &&
>> + !IS_ENABLED(CONFIG_PAGE_POISONING_NO_SANITY)))
>> + walk_free_mem_block(vb, 0, &virtio_balloon_send_free_pages);
>> /*
>> * End by sending the stop id to the host with an outbuf. Use the
>> * non-batching mode here to trigger a kick after adding the stop id.
> PAGE_POISONING_ZERO is actually OK.
>
> But I really would prefer it that we still send pages to host,
> otherwise debugging becomes much harder.
>
> And it does not have to be completely useless, even though
> you can not discard them as they would be zero-filled then.
>
> How about a config field telling host what should be there in the free
> pages? This way even though host can not discard them, host can send
> them out without reading them, still a win.
>
>
Since this poison value comes with the free page reporting feature, how
about sending the poison value via the free_page_vq, along with the cmd
id in the outbuf? That is, use the following interface:
struct virtio_balloon_free_page_vq_hdr {
bool page_poisoning;
__virtio32 poison_value;
__virtio32 cmd_id;
}
We need "bool page_poisoning" because "poison_value=0" doesn't tell
whether page poising is in use by the guest. PAGE_POISONING_ZERO sets
"page_poisoning=true, poisoning_value=0", and the host will send the
0-filled pages to the destination (if not sending 0-filled pages, the
destination host would offer non-zero pages to the guest)
The host can discard free pages only when "page_poisoning=false".
Best,
Wei
^ permalink raw reply
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