Re: [PATCH v4] qla1280: Reduce can_queue to 512

[James Bottomley <jejb@linux.vnet.ibm.com>]

On Mon, 2016-04-25 at 16:44 +0200, Johannes Thumshirn wrote:
> The qla1280 driver sets the scsi_host_template's can_queue field to
> 0xfffff
> which results in an allocation failure when allocating the block
> layer tags
> for the driver's queues like the one shown below:
> 
> [    4.804166] scsi host0: QLogic QLA1040 PCI to SCSI Host Adapter
> Firmware version:  7.65.06, Driver version 3.27.1
> [    4.804174] ------------[ cut here ]------------
> [    4.804184] WARNING: CPU: 2 PID: 305 at mm/page_alloc.c:2989
> alloc_pages_nodemask+0xae8/0xbc0()
> [    4.804186] Modules linked in: amdkfd amd_iommu_v2 radeon
> i2c_algo_bit m_kms_helper ttm drm megaraid_sas serio_raw 8021q garp
> bnx2 stp llc mrp nhme qla1280(+) fjes
> [    4.804208] CPU: 2 PID: 305 Comm: systemd-udevd Not tainted 4.6
> -201.fc22.x86_64 #1
> [    4.804210] Hardware name: Google Enterprise Search
> Appliance/0DT021, OS 1.1.2 08/14/2006
> [    4.804212]  0000000000000286 000000002f01064c ffff88042985b710
> ffffff813b542e
> [    4.804216]  0000000000000000 ffffffff81a75024 ffff88042985b748
> ffffff810a40f2
> [    4.804220]  0000000000000000 0000000000000000 000000000000000b
> 00000000000000
> [    4.804223] Call Trace:
> [    4.804231]  [<ffffffff813b542e>] dump_stack+0x63/0x85
> [    4.804236]  [<ffffffff810a40f2>] warn_slowpath_common+0x82/0xc0
> [    4.804239]  [<ffffffff810a423a>] warn_slowpath_null+0x1a/0x20
> [    4.804242]  [<ffffffff811b75e8>]
> __alloc_pages_nodemask+0xae8/0xbc0
> [    4.804247]  [<ffffffff817a002e>] ?
> _raw_spin_unlock_irqrestore+0xe/0x10
> [    4.804251]  [<ffffffff811908be>] ? irq_work_queue+0x8e/0xa0
> [    4.804256]  [<ffffffff810fa10a>] ? console_unlock+0x20a/0x540
> [    4.804262]  [<ffffffff812029cc>] alloc_pages_current+0x8c/0x110
> [    4.804265]  [<ffffffff811b5159>] alloc_kmem_pages+0x19/0x90
> [    4.804268]  [<ffffffff811d2efe>] kmalloc_order_trace+0x2e/0xe0
> [    4.804272]  [<ffffffff8120e6d2>] __kmalloc+0x232/0x260
> [    4.804277]  [<ffffffff8138990d>] init_tag_map+0x3d/0xc0
> [    4.804290]  [<ffffffff813899d5>] __blk_queue_init_tags+0x45/0x80
> [    4.804293]  [<ffffffff81389a24>] blk_init_tags+0x14/0x20
> [    4.804298]  [<ffffffff81520e60>]
> scsi_add_host_with_dma+0x80/0x300
> [    4.804305]  [<ffffffffa000fec3>] qla1280_probe_one+0x683/0x9ef
> [qla1280]
> [    4.804309]  [<ffffffff81401115>] local_pci_probe+0x45/0xa0
> [    4.804312]  [<ffffffff814024fd>] pci_device_probe+0xfd/0x140
> [    4.804316]  [<ffffffff814ef1d2>] driver_probe_device+0x222/0x490
> [    4.804319]  [<ffffffff814ef4c4>] __driver_attach+0x84/0x90
> [    4.804321]  [<ffffffff814ef440>] ?
> driver_probe_device+0x490/0x490
> [    4.804324]  [<ffffffff814eccac>] bus_for_each_dev+0x6c/0xc0
> [    4.804326]  [<ffffffff814ee98e>] driver_attach+0x1e/0x20
> [    4.804328]  [<ffffffff814ee4cb>] bus_add_driver+0x1eb/0x280
> [    4.804331]  [<ffffffffa0015000>] ? 0xffffffffa0015000
> [    4.804333]  [<ffffffff814efd80>] driver_register+0x60/0xe0
> [    4.804336]  [<ffffffff81400a5c>] __pci_register_driver+0x4c/0x50
> [    4.804339]  [<ffffffffa00151ce>] qla1280_init+0x1ce/0x1000
> [qla1280]
> [    4.804341]  [<ffffffffa0015000>] ? 0xffffffffa0015000
> [    4.804345]  [<ffffffff81002123>] do_one_initcall+0xb3/0x200
> [    4.804348]  [<ffffffff8120d086>] ?
> kmem_cache_alloc_trace+0x196/0x210
> [    4.804352]  [<ffffffff811aba7e>] ? do_init_module+0x27/0x1cb
> [    4.804354]  [<ffffffff811abab6>] do_init_module+0x5f/0x1cb
> [    4.804358]  [<ffffffff8112a6e0>] load_module+0x2040/0x2680
> [    4.804360]  [<ffffffff81126e40>] ? __symbol_put+0x60/0x60
> [    4.804363]  [<ffffffff8112ae69>] SYSC_init_module+0x149/0x190
> [    4.804366]  [<ffffffff8112af9e>] SyS_init_module+0xe/0x10
> [    4.804369]  [<ffffffff817a05ae>]
> entry_SYSCALL_64_fastpath+0x12/0x71
> [    4.804371] ---[ end trace 0ea3b625f86705f7 ]---
> [    4.804581] qla1280: probe of 0000:11:04.0 failed with error -12
> 
> Reduce can_queue to 512 to solve the allocation error.
> 
> Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
> Cc: Laura Abbott <labbott@redhat.com>
> Cc: Michael Reed <mdr@sgi.com>
> Cc: stable@vger.kernel.org

If you're going to cc stable, don't force them to backport it forever
(and fill up my mailbox), give the limit (version 4.4) and explain why
in the change log (because the breakage was introduced by commit
4d513ac31bd02a3c9b69ef04444f36c196f9a9d).  On the subject of being
helpful to others: the kernel warning looks scary, but contains no
useful information.  The actual reason is that with hostwide tags, we
now allocate an array with one pointer per tag up to the host
->can_queue limit, which for qla1280 was set to machine infinity of
65535 meaning an allocation of 512kb on a 64 bit system.

James