From: Michal Hocko <mhocko@kernel.org>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org
Subject: Re: [RFC] free_pages stuff
Date: Tue, 5 Jan 2016 16:42:07 +0100 [thread overview]
Message-ID: <20160105154207.GF15324@dhcp22.suse.cz> (raw)
In-Reply-To: <20160105152602.GR9938@ZenIV.linux.org.uk>
On Tue 05-01-16 15:26:02, Al Viro wrote:
> On Tue, Jan 05, 2016 at 02:59:03PM +0100, Michal Hocko wrote:
>
> > > 3) vmalloc() is for large allocations. They will be page-aligned,
> > > but *not* physically contiguous. OTOH, large physically contiguous
> > > allocations are generally a bad idea. Unlike other allocators, there's
> > > no variant that could be used in interrupt; freeing is possible there,
> > > but allocation is not. Note that non-blocking variant *does* exist -
> > > __vmalloc(size, GFP_ATOMIC, PAGE_KERNEL) can be used in atomic
> > > contexts; it's the interrupt ones that are no-go.
>
> The last sentence I'd put into that part was complete crap...
>
> > It is also hardcoded GFP_KERNEL context so a usage from NOFS context
> > needs a special treatment.
>
> ... in part because of this. GFP_ATOMIC __vmalloc() will be anything but,
> and the only caller passing that is almost certainly bogus.
Agreed as just replied in the other email thread which I have noticed
only now.
> As for NOFS/NOIO,
> I wonder if we should apply that special treatment inside __vmalloc_area_node
> rather than in callers; see the current thread on linux-mm for details...
That would make a lot of sense to me. Spreading the _special_ treatment
all over the kernel is certainly worse.
> Another interesting issue is __GFP_HIGHMEM meaning for kmalloc and __vmalloc
> resp. (should never be passed to kmalloc, should almost always be passed
> to __vmalloc - the former needs pages mapped in kernel space, the latter
> probably never needs a separate kernel alias for the data pages, to such
> degree that I'm not sure if we shouldn't _force_ __GFP_HIGHMEM for data pages
> allocation in __vmalloc_area_node())
I would have to think about this one some more. Let's not fragment the
discussion and continue in that email thread:
http://lkml.kernel.org/r/20160103071246.GK9938%40ZenIV.linux.org.uk
--
Michal Hocko
SUSE Labs
prev parent reply other threads:[~2016-01-05 15:42 UTC|newest]
Thread overview: 94+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-21 23:46 [RFC] free_pages stuff Al Viro
2015-12-21 23:46 ` [POC][PATCH 01/83] switch free_page() from unsigned long to const void * Al Viro
2015-12-21 23:46 ` [POC][PATCH 02/83] switch free_pages() " Al Viro
2015-12-21 23:46 ` [POC][PATCH 03/83] switch get_zeroed_page() to returning " Al Viro
2015-12-21 23:46 ` [POC][PATCH 04/83] kill unused {get,free}_user_page() Al Viro
2015-12-21 23:46 ` [POC][PATCH 05/83] switch copy_mount_options to storing void * instead of unsigned long Al Viro
2015-12-21 23:46 ` [POC][PATCH 06/83] drivers/net/wireless/libertas/debugfs.c: get rid of pointless casts Al Viro
2015-12-21 23:46 ` [POC][PATCH 07/83] drivers/net/wireless/mwifiex/debugfs.c: " Al Viro
2015-12-21 23:46 ` [POC][PATCH 08/83] affs_evict_inode(): " Al Viro
2015-12-21 23:46 ` [POC][PATCH 09/83] configfs_follow_link(): " Al Viro
2015-12-21 23:46 ` [POC][PATCH 10/83] kernfs_iop_follow_link(): " Al Viro
2015-12-21 23:46 ` [POC][PATCH 11/83] sound/oss/vidc: keep dma_buf[] as pointers Al Viro
2015-12-21 23:46 ` [POC][PATCH 12/83] drivers/tty: get rid of pointless casts Al Viro
2015-12-21 23:46 ` [POC][PATCH 13/83] rds: keep pointers in ->m_page_addrs[] Al Viro
2015-12-21 23:46 ` [POC][PATCH 14/83] proc_dev_atm_read(): get rid of pointless casts Al Viro
2015-12-21 23:46 ` [POC][PATCH 15/83] qib get_map_page(): " Al Viro
2015-12-21 23:46 ` [POC][PATCH 16/83] user_namespace: " Al Viro
2015-12-21 23:46 ` [POC][PATCH 17/83] ftrace: " Al Viro
2015-12-21 23:46 ` [POC][PATCH 18/83] sysctl: " Al Viro
2015-12-21 23:46 ` [POC][PATCH 19/83] xenstored_local_init(): " Al Viro
2015-12-21 23:46 ` [POC][PATCH 20/83] staging/rdma: " Al Viro
2015-12-21 23:46 ` [POC][PATCH 21/83] c6x: remove unused macros Al Viro
2015-12-21 23:46 ` [POC][PATCH 22/83] [davinci] ccdc_update_raw_params() frees the wrong thing Al Viro
2015-12-21 23:46 ` [POC][PATCH 23/83] fd_dma_mem_free(): pass address as void * instead of unsigned long Al Viro
2015-12-21 23:46 ` [POC][PATCH 24/83] ppc: keep ->hpt_virt as a pointer Al Viro
2015-12-21 23:46 ` [POC][PATCH 25/83] dma_4u_alloc_coherent(): don't mix virtual and physical addresses Al Viro
2015-12-21 23:46 ` [POC][PATCH 26/83] dma_4v_alloc_coherent(): " Al Viro
2015-12-21 23:47 ` [POC][PATCH 27/83] new helper: get_dma_pages() Al Viro
2015-12-21 23:47 ` [POC][PATCH 28/83] make fd_dma_mem_alloc/nodma_mem_alloc return a pointer Al Viro
2015-12-21 23:47 ` [POC][PATCH 29/83] switch the remaining users of __get_dma_pages() to get_dma_pages() Al Viro
2015-12-21 23:47 ` [POC][PATCH 30/83] sparc: get rid of pointless casts Al Viro
2015-12-21 23:47 ` [POC][PATCH 31/83] efficeon: " Al Viro
2015-12-21 23:47 ` [POC][PATCH 32/83] lguest: " Al Viro
2015-12-21 23:47 ` [POC][PATCH 33/83] drivers/pci: " Al Viro
2015-12-21 23:47 ` [POC][PATCH 34/83] drivers/s390: ger " Al Viro
2015-12-21 23:47 ` [POC][PATCH 35/83] s390 kvm: get " Al Viro
2015-12-21 23:47 ` [POC][PATCH 36/83] pcibios: " Al Viro
2015-12-21 23:47 ` [POC][PATCH 37/83] ste_dma40: " Al Viro
2015-12-21 23:47 ` [POC][PATCH 38/83] usb_mon: " Al Viro
2015-12-21 23:47 ` [POC][PATCH 39/83] gnttab_end_foreign_access(): switch the last argument to void * Al Viro
2015-12-21 23:47 ` [POC][PATCH 40/83] nios2: dma_free_coherent(): get rid of pointless casts Al Viro
2015-12-21 23:47 ` [POC][PATCH 41/83] hsi: " Al Viro
2015-12-21 23:47 ` [POC][PATCH 42/83] simserial: " Al Viro
2015-12-21 23:47 ` [POC][PATCH 43/83] arm64 vdso: " Al Viro
2015-12-21 23:47 ` [POC][PATCH 44/83] cris free_init_page(): switch to __free_page() Al Viro
2015-12-21 23:47 ` [POC][PATCH 45/83] arm: switch kvm_arm_hyp_stack_page to void * Al Viro
2015-12-21 23:47 ` [POC][PATCH 46/83] frv consistent_alloc(): switch page " Al Viro
2015-12-21 23:47 ` [POC][PATCH 47/83] ia64: uncached_add_chunk(): switch to __free_pages() Al Viro
2015-12-21 23:47 ` [POC][PATCH 48/83] jfs_readdir(): make dirent_buf a pointer Al Viro
2015-12-21 23:47 ` [POC][PATCH 49/83] get rid of casts in alloc_exact stuff Al Viro
2015-12-21 23:47 ` [POC][PATCH 50/83] s390 cmm: get rid of pointless casts Al Viro
2015-12-21 23:47 ` [POC][PATCH 51/83] microblaze consistent_alloc(): " Al Viro
2015-12-21 23:47 ` [POC][PATCH 52/83] devm_{get_}free_pages(): switch to pointers Al Viro
2015-12-21 23:47 ` [POC][PATCH 53/83] cavium: (partially) get rid of cargo-culting in allocator Al Viro
2015-12-21 23:47 ` [POC][PATCH 54/83] um: store stacks as pointers Al Viro
2015-12-21 23:47 ` [POC][PATCH 55/83] sh: get rid of pointless casts Al Viro
2015-12-21 23:47 ` [POC][PATCH 56/83] amd_gart_64: " Al Viro
2015-12-21 23:47 ` [POC][PATCH 57/83] iwlegacy: " Al Viro
2015-12-21 23:47 ` [POC][PATCH 58/83] iwlwifi: " Al Viro
2015-12-21 23:47 ` [POC][PATCH 59/83] add pointer-returning variants of __get_free_pages/__get_free_page Al Viro
2015-12-21 23:47 ` [POC][PATCH 60/83] switch obvious cases to get_free_pages() Al Viro
2015-12-21 23:47 ` [POC][PATCH 61/83] switch obvious cases to get_free_page() Al Viro
2015-12-21 23:47 ` [POC][PATCH 62/83] m68k: switch pte_alloc_one_kernel() " Al Viro
2015-12-21 23:47 ` [POC][PATCH 63/83] switch kvmppc_core_vcpu_create_pr() " Al Viro
2015-12-21 23:47 ` [POC][PATCH 64/83] drivers/video/fbdev: switch to get_free_pages() Al Viro
2015-12-21 23:47 ` [POC][PATCH 65/83] um: switch to get_free_page() Al Viro
2015-12-21 23:47 ` [POC][PATCH 66/83] switch xen_get_swiotlb_free_pages() to returning a pointer Al Viro
2015-12-21 23:47 ` [POC][PATCH 67/83] mn10300 dma_alloc_coherent(): switch to get_free_pages() Al Viro
2015-12-21 23:47 ` [POC][PATCH 68/83] switch ps3_dma_map() and ps3_dma_region_ops->map() instances to physical address Al Viro
2015-12-21 23:47 ` [POC][PATCH 69/83] ps3_alloc_coherent(): get rid of pointless casts Al Viro
2015-12-21 23:47 ` [POC][PATCH 70/83] s390_dma_alloc(): page_to_phys() result is always a multiple of PAGE_SIZE Al Viro
2015-12-21 23:47 ` [POC][PATCH 71/83] s390_dma_alloc(): use page_address() Al Viro
2015-12-21 23:47 ` [POC][PATCH 72/83] [powerpc] switch cmm_page_array->pages[] to pointers Al Viro
2015-12-21 23:47 ` [POC][PATCH 73/83] niu.c: get rid of pointless casts Al Viro
2015-12-21 23:47 ` [POC][PATCH 74/83] [s390] switch pcpu_alloc_lowcore() to get_free_page() Al Viro
2015-12-21 23:47 ` [POC][PATCH 75/83] kill __get_free_page() Al Viro
2015-12-21 23:47 ` [POC][PATCH 76/83] [mips, s390, score] turn empty_zero_page into pointer Al Viro
2015-12-21 23:47 ` [POC][PATCH 77/83] sparc: switch to get_free_pages() Al Viro
2015-12-21 23:47 ` [POC][PATCH 78/83] x86: " Al Viro
2015-12-21 23:47 ` [POC][PATCH 79/83] s390: turn suspend_zero_pages into a pointer Al Viro
2015-12-21 23:47 ` [POC][PATCH 80/83] [sun3] try to sort dvma types out Al Viro
2015-12-21 23:47 ` [POC][PATCH 81/83] sba_iommu: get rid of pointless casts Al Viro
2015-12-21 23:47 ` [POC][PATCH 82/83] media/platform/omap: " Al Viro
2015-12-21 23:47 ` [POC][PATCH 83/83] nios2: " Al Viro
2015-12-22 0:03 ` [RFC] free_pages stuff Linus Torvalds
2015-12-22 1:04 ` Al Viro
[not found] ` <CA+55aFy9NrV_RnziN9z3p5O6rv1A0mirhLD0hL7Wrb77+YyBeg@mail.gmail.com>
2015-12-22 1:23 ` Linus Torvalds
2015-12-22 3:10 ` Al Viro
2015-12-22 2:22 ` Al Viro
2015-12-22 8:21 ` Geert Uytterhoeven
2015-12-22 21:04 ` Al Viro
2016-01-05 13:59 ` Michal Hocko
2016-01-05 15:26 ` Al Viro
2016-01-05 15:42 ` Michal Hocko [this message]
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