1:46 a.m.
Mel Gorman <mgorman(a)techsingularity.net> writes:
On Wed, Dec 02, 2015 at 03:15:29PM +0100, Michal Hocko wrote:
> > > I didn't mention this allocation failure because I am not sure it is
> > > really related.
> > >
> >
> > I'm fairly sure it is. The failure is an allocation site that cannot
> > sleep but did not specify __GFP_HIGH.
>
> yeah but this was the case even before your patch. As the caller used
> GFP_ATOMIC then it got __GFP_ATOMIC after your patch so it still
> managed to do ALLOC_HARDER. I would agree if this was an explicit
> GFP_NOWAIT. Unless I am missing something your patch hasn't changed the
> behavior for this particular allocation.
>
You're right. I think it's this hunk that is the problem.
@@ -1186,7 +1186,7 @@ static struct request *blk_mq_map_request(struct
request_queue *q,
ctx = blk_mq_get_ctx(q);
hctx = q->mq_ops->map_queue(q, ctx->cpu);
blk_mq_set_alloc_data(&alloc_data, q,
- __GFP_WAIT|GFP_ATOMIC, false, ctx, hctx);
+ __GFP_WAIT|__GFP_HIGH, false, ctx, hctx);
rq = __blk_mq_alloc_request(&alloc_data, rw);
ctx = alloc_data.ctx;
hctx = alloc_data.hctx;
This specific path at this patch is not waking kswapd any more when it
should. A series of allocations there could hit the watermarks and never wake
kswapd and then be followed by an atomic allocation failure that woke kswapd.
This bug gets fixed later by the commit 71baba4b92dc ("mm, page_alloc:
rename __GFP_WAIT to __GFP_RECLAIM") so it's not a bug in the current
kernel. However, it happens to break bisection and would be caught if each
individual commit was tested.
Your __GFP_HIGH patch is still fine although not the direct fix for this
specific problem. Commit 71baba4b92dc is.
Ying, does the page allocation failure messages happen when the whole
series is applied? i.e. is 4.4-rc3 ok?
There are allocation errors for 4.4-rc3 too. dmesg is attached.
[ 54.970840] kworker/u4:0: page allocation failure: order:0, mode:0x2204000
[ 54.973161] CPU: 1 PID: 6 Comm: kworker/u4:0 Not tainted 4.4.0-rc3 #1
[ 54.975179] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1
04/01/2014
[ 54.980562] Workqueue: writeback wb_workfn (flush-253:0)
[ 54.982289] 0000000000000000 ffff880035ac7098 ffffffff81410ad2 0000000002204000
[ 54.985438] ffff880035ac7120 ffffffff811724cb ffff880037586b50 0000000000000040
[ 54.988746] 0000000000000000 0000000000000040 ffffffff00ac70e0 ffffffff00000000
[ 54.991669] Call Trace:
[ 54.992754] [<ffffffff81410ad2>] dump_stack+0x4b/0x69
[ 54.994433] [<ffffffff811724cb>] warn_alloc_failed+0xdb/0x140
[ 54.996134] [<ffffffff811762b9>] __alloc_pages_nodemask+0x949/0xb40
[ 54.997846] [<ffffffff811be2c2>] alloc_pages_current+0x92/0x120
[ 54.999494] [<ffffffff811c8bfc>] new_slab+0x3dc/0x480
[ 55.001007] [<ffffffff811c9421>] ___slab_alloc+0x351/0x440
[ 55.002588] [<ffffffff814e7fcd>] ? alloc_indirect+0x1d/0x50
[ 55.004268] [<ffffffff8132270f>] ? xfs_btree_insrec+0x47f/0x700
[ 55.005926] [<ffffffff813206e9>] ? xfs_btree_delrec+0x5a9/0x1380
[ 55.007592] [<ffffffff814e7fcd>] ? alloc_indirect+0x1d/0x50
[ 55.009281] [<ffffffff811c9530>] __slab_alloc+0x20/0x40
[ 55.010827] [<ffffffff811ca03d>] __kmalloc+0x20d/0x260
[ 55.012367] [<ffffffff814e7fcd>] alloc_indirect+0x1d/0x50
[ 55.014040] [<ffffffff814e82cc>] virtqueue_add_sgs+0x2cc/0x3a0
[ 55.015683] [<ffffffff8157b240>] __virtblk_add_req+0xb0/0x1f0
[ 55.017300] [<ffffffff81307944>] ? xfs_alloc_update_counters+0x44/0x50
[ 55.019759] [<ffffffff813ec524>] ? blk_rq_map_sg+0x1f4/0x510
[ 55.021371] [<ffffffff8157b492>] virtio_queue_rq+0x112/0x280
[ 55.022978] [<ffffffff813f0647>] __blk_mq_run_hw_queue+0x1d7/0x370
[ 55.024674] [<ffffffff813f044f>] blk_mq_run_hw_queue+0x9f/0xc0
[ 55.026307] [<ffffffff813f196a>] blk_mq_insert_requests+0xfa/0x1a0
[ 55.028003] [<ffffffff813f26b3>] blk_mq_flush_plug_list+0x123/0x140
[ 55.029710] [<ffffffff813e7c77>] blk_flush_plug_list+0xa7/0x200
[ 55.031363] [<ffffffff813f1bec>] blk_sq_make_request+0x1dc/0x3b0
[ 55.033025] [<ffffffff813e5b0c>] ? generic_make_request_checks+0x24c/0x530
[ 55.034829] [<ffffffff813e6341>] generic_make_request+0xf1/0x1e0
[ 55.036508] [<ffffffff813e6497>] submit_bio+0x67/0x150
[ 55.038034] [<ffffffff8133cd61>] xfs_submit_ioend_bio+0x31/0x40
[ 55.039797] [<ffffffff8133ce51>] xfs_submit_ioend+0xe1/0x120
[ 55.041410] [<ffffffff8133e183>] xfs_vm_writepage+0x2a3/0x630
[ 55.043038] [<ffffffff811771a3>] __writepage+0x13/0x30
[ 55.044568] [<ffffffff811794bc>] write_cache_pages+0x22c/0x4c0
[ 55.046214] [<ffffffff81177190>] ? wb_position_ratio+0x1f0/0x1f0
[ 55.047888] [<ffffffff81179793>] generic_writepages+0x43/0x60
[ 55.049520] [<ffffffff8133d54e>] xfs_vm_writepages+0x4e/0x60
[ 55.051130] [<ffffffff8117a49e>] do_writepages+0x1e/0x30
[ 55.052694] [<ffffffff81216b05>] __writeback_single_inode+0x45/0x2e0
[ 55.054410] [<ffffffff812172e1>] writeback_sb_inodes+0x271/0x4d0
[ 55.056075] [<ffffffff812175c9>] __writeback_inodes_wb+0x89/0xc0
[ 55.057749] [<ffffffff812178ea>] wb_writeback+0x23a/0x2c0
[ 55.059312] [<ffffffff8121806f>] wb_workfn+0x20f/0x390
[ 55.060846] [<ffffffff81091257>] process_one_work+0x157/0x420
[ 55.062466] [<ffffffff81091eb9>] worker_thread+0x69/0x4a0
[ 55.064030] [<ffffffff81091e50>] ? rescuer_thread+0x380/0x380
[ 55.065655] [<ffffffff8109741f>] kthread+0xef/0x110
[ 55.067141] [<ffffffff81097330>] ? kthread_park+0x60/0x60
[ 55.068713] [<ffffffff818c5f8f>] ret_from_fork+0x3f/0x70
[ 55.070255] [<ffffffff81097330>] ? kthread_park+0x60/0x60
[ 55.071830] Mem-Info:
[ 55.072889] active_anon:5024 inactive_anon:1642 isolated_anon:0
[ 55.072889] active_file:22984 inactive_file:106547 isolated_file:25
[ 55.072889] unevictable:93684 dirty:7732 writeback:13026 unstable:0
[ 55.072889] slab_reclaimable:13082 slab_unreclaimable:3604
[ 55.072889] mapped:2866 shmem:1687 pagetables:876 bounce:0
[ 55.072889] free:1931 free_pcp:45 free_cma:0
[ 55.081979] Node 0 DMA free:3948kB min:60kB low:72kB high:88kB active_anon:328kB
inactive_anon:124kB active_file:1680kB inactive_file:1704kB unevictable:6936kB
isolated(anon):0kB isolated(file):0kB present:15992kB managed:15908kB mlocked:0kB
dirty:52kB writeback:76kB mapped:440kB shmem:124kB slab_reclaimable:472kB
slab_unreclaimable:232kB kernel_stack:80kB pagetables:84kB unstable:0kB bounce:0kB
free_pcp:0kB local_pcp:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:0
all_unreclaimable? no
[ 55.093512] lowmem_reserve[]: 0 972 972 972
[ 55.095362] Node 0 DMA32 free:3776kB min:3824kB low:4780kB high:5736kB
active_anon:19768kB inactive_anon:6444kB active_file:90256kB inactive_file:424484kB
unevictable:367800kB isolated(anon):0kB isolated(file):100kB present:1032064kB
managed:997492kB mlocked:0kB dirty:30876kB writeback:52028kB mapped:11024kB shmem:6624kB
slab_reclaimable:51856kB slab_unreclaimable:14184kB kernel_stack:2864kB pagetables:3420kB
unstable:0kB bounce:0kB free_pcp:180kB local_pcp:0kB free_cma:0kB writeback_tmp:0kB
pages_scanned:100 all_unreclaimable? no
[ 55.107443] lowmem_reserve[]: 0 0 0 0
[ 55.109213] Node 0 DMA: 4*4kB (U) 3*8kB (UE) 2*16kB (UM) 1*32kB (E) 0*64kB 2*128kB (UM)
2*256kB (UM) 2*512kB (ME) 2*1024kB (ME) 0*2048kB 0*4096kB = 3944kB
[ 55.114800] Node 0 DMA32: 90*4kB (UE) 13*8kB (UE) 10*16kB (UME) 7*32kB (UME) 46*64kB
(ME) 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 3792kB
[ 55.120027] Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0
hugepages_size=2048kB
[ 55.122668] 224906 total pagecache pages
[ 55.123990] 0 pages in swap cache
[ 55.125207] Swap cache stats: add 0, delete 0, find 0/0
[ 55.126738] Free swap = 0kB
[ 55.127890] Total swap = 0kB
[ 55.129039] 262014 pages RAM
[ 55.130190] 0 pages HighMem/MovableOnly
[ 55.131495] 8664 pages reserved
[ 55.132690] 0 pages hwpoisoned
[ 55.133868] SLUB: Unable to allocate memory on node -1 (gfp=0x2080000)
[ 55.135607] cache: kmalloc-2048, object size: 2048, buffer size: 2048, default order:
3, min order: 0
[ 55.138454] node 0: slabs: 22, objs: 352, free: 0
Best Regards,
Huang, Ying
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