Re: Possible deadlock in v4.14.15 contention on shrinker_rwsem in shrink_slab()

[Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>]

Eric Wheeler wrote:
> I just tried v4.9.78 and we still get the deadlock. I've backported your 
> MemAlloc timing patch and yout timing is included in the output.  Both 
> full sysrq traces (30 seconds apart) are available here and I made sure it 
> includes both "Showing busy workqueues and worker pools" sections:
> 
>   https://www.linuxglobal.com/static/2018-01-27-hv1-deadlock-v4.9.78
> 
> # ps -eo pid,lstart,cmd,stat |grep D
>   PID                  STARTED CMD                         STAT
> 16127 Sat Jan 27 05:24:29 2018 crm_node -N 2               D    << Both in D state
> 22444 Sat Jan 27 05:39:50 2018 rsync --server --sender -vl DNs  << Both in D state
> 

Thank you. Although the capture is still incomplete, I noticed that
there was a surprising entry.

crm_node was stalling at page fault for 33950 seconds!
That is, crm_node already started stalling at uptime = 45375.

----------
[79325.124062] MemAlloc: crm_node(16127) flags=0xc00900 switches=10 seq=441 gfp=0x24200ca(GFP_HIGHUSER_MOVABLE) order=0 delay=33950065 uninterruptible
[79325.125113]  ffff8cf6d750dd00 0000000000000000 ffff8cf74b9d5800 ffff8cf76fd19940
[79325.125684]  ffff8cf6c3d84200 ffffada2a17af6c8 ffffffff8e7178f5 0000000000000000
[79325.126245]  0000000000000000 0000000000000000 ffff8cf6c3d84200 7fffffffffffffff
[79325.126800] Call Trace:
[79325.127339]  [<ffffffff8e7178f5>] ? __schedule+0x195/0x630
[79325.127985]  [<ffffffff8e718630>] ? bit_wait+0x50/0x50
[79325.128519]  [<ffffffff8e717dc6>] schedule+0x36/0x80
[79325.129040]  [<ffffffff8e71afa6>] schedule_timeout+0x1e6/0x320
[79325.129560]  [<ffffffff8e718630>] ? bit_wait+0x50/0x50
[79325.130100]  [<ffffffff8e7176f6>] io_schedule_timeout+0xa6/0x110
[79325.130683]  [<ffffffff8e71864b>] bit_wait_io+0x1b/0x60
[79325.131199]  [<ffffffff8e718286>] __wait_on_bit_lock+0x86/0xd0
[79325.131723]  [<ffffffff8e1acb22>] __lock_page+0x82/0xb0
[79325.132238]  [<ffffffff8e0e9e00>] ? autoremove_wake_function+0x40/0x40
[79325.132765]  [<ffffffff8e1ae63b>] pagecache_get_page+0x16b/0x230
[79325.133284]  [<ffffffff8e1ca3da>] shmem_unused_huge_shrink+0x28a/0x330
[79325.133814]  [<ffffffff8e1ca4a7>] shmem_unused_huge_scan+0x27/0x30
[79325.134338]  [<ffffffff8e23f941>] super_cache_scan+0x181/0x190
[79325.134875]  [<ffffffff8e1c1ab1>] shrink_slab+0x261/0x470
[79325.135386]  [<ffffffff8e1c6588>] shrink_node+0x108/0x310
[79325.135904]  [<ffffffff8e1c6927>] node_reclaim+0x197/0x210
[79325.136458]  [<ffffffff8e1b5dd8>] get_page_from_freelist+0x168/0x9f0
[79325.137023]  [<ffffffff8e1adc8e>] ? find_get_entry+0x1e/0x100
[79325.137560]  [<ffffffff8e1ca9c5>] ? shmem_getpage_gfp+0xf5/0xbb0
[79325.138061]  [<ffffffff8e1b77ae>] __alloc_pages_nodemask+0x10e/0x2d0
[79325.138619]  [<ffffffff8e207d08>] alloc_pages_current+0x88/0x120
[79325.139117]  [<ffffffff8e070287>] pte_alloc_one+0x17/0x40
[79325.139626]  [<ffffffff8e1e117e>] __pte_alloc+0x1e/0x100
[79325.140138]  [<ffffffff8e1e3622>] alloc_set_pte+0x4f2/0x560
[79325.140698]  [<ffffffff8e1e3770>] do_fault+0xe0/0x620
[79325.141168]  [<ffffffff8e1e5504>] handle_mm_fault+0x644/0xdd0
[79325.141667]  [<ffffffff8e06a96e>] __do_page_fault+0x25e/0x4f0
[79325.142163]  [<ffffffff8e06ac30>] do_page_fault+0x30/0x80
[79325.142660]  [<ffffffff8e003b55>] ? do_syscall_64+0x175/0x180
[79325.143132]  [<ffffffff8e71dae8>] page_fault+0x28/0x30
----------

You took SysRq-t after multiple processes (in this case, crm_node and rsync)
got stuck, didn't you? I feel anxious about LIST_POISON1 (dead000000000100) and
LIST_POISON2 (dead000000000200) are showing up at rsync side.

----------
[79325.156361] rsync           D    0 22444  22441 0x00000080
[79325.156871]  ffff8cf3b8437440 0000000000000000 ffff8cf74b9d1600 ffff8cf76fc59940
[79325.157307]  ffff8cf3eef74200 ffffada2a0e17b18 ffffffff8e7178f5 dead000000000100
[79325.157764]  dead000000000200 ffff8cf6db9101a8 ffff8cf3eef74200 7fffffffffffffff
[79325.158225] Call Trace:
[79325.158690]  [<ffffffff8e7178f5>] ? __schedule+0x195/0x630
[79325.159142]  [<ffffffff8e718630>] ? bit_wait+0x50/0x50
[79325.159604]  [<ffffffff8e717dc6>] schedule+0x36/0x80
[79325.160053]  [<ffffffff8e71afa6>] schedule_timeout+0x1e6/0x320
[79325.160536]  [<ffffffff8e0de21c>] ? enqueue_entity+0x3bc/0x570
[79325.160984]  [<ffffffff8e11bf5b>] ? ktime_get+0x3b/0xb0
[79325.161450]  [<ffffffff8e718630>] ? bit_wait+0x50/0x50
[79325.161891]  [<ffffffff8e7176f6>] io_schedule_timeout+0xa6/0x110
[79325.162337]  [<ffffffff8e71864b>] bit_wait_io+0x1b/0x60
[79325.162787]  [<ffffffff8e718286>] __wait_on_bit_lock+0x86/0xd0
[79325.163231]  [<ffffffff8e1acb22>] __lock_page+0x82/0xb0
[79325.163681]  [<ffffffff8e0e9e00>] ? autoremove_wake_function+0x40/0x40
[79325.164133]  [<ffffffff8e1addd1>] find_lock_entry+0x61/0x80
[79325.164597]  [<ffffffff8e1ca9c5>] shmem_getpage_gfp+0xf5/0xbb0
[79325.165053]  [<ffffffff8e1cb9b9>] shmem_file_read_iter+0x159/0x310
[79325.165516]  [<ffffffff8e23b2ff>] __vfs_read+0xdf/0x130
[79325.165966]  [<ffffffff8e23ba2c>] vfs_read+0x8c/0x130
[79325.166430]  [<ffffffff8e23cf95>] SyS_read+0x55/0xc0
[79325.166865]  [<ffffffff8e003a47>] do_syscall_64+0x67/0x180
[79325.167292]  [<ffffffff8e71c530>] entry_SYSCALL64_slow_path+0x25/0x25
----------

> 
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> crm_node        D    0 16127  16126 0x00000080
> MemAlloc: crm_node(16127) flags=0xc00900 switches=10 seq=441 gfp=0x24200ca(GFP_HIGHUSER_MOVABLE) order=0 delay=209469 uninterruptible

At this point, crm_node already stalled for 209 seconds. Since switches= and
seq= did not change until you took SysRq-t, crm_node kept sleeping.

> ffff8cf6d750dd00 0000000000000000 ffff8cf74b9d5800 ffff8cf76fd19940
> ffff8cf6c3d84200 ffffada2a17af6c8 ffffffff8e7178f5 0000000000000000
> 0000000000000000 0000000000000000 ffff8cf6c3d84200 7fffffffffffffff
> Call Trace:
> [<ffffffff8e7178f5>] ? __schedule+0x195/0x630
> [<ffffffff8e718630>] ? bit_wait+0x50/0x50
> [<ffffffff8e717dc6>] schedule+0x36/0x80
> [<ffffffff8e71afa6>] schedule_timeout+0x1e6/0x320
> [<ffffffff8e718630>] ? bit_wait+0x50/0x50
> [<ffffffff8e7176f6>] io_schedule_timeout+0xa6/0x110
> [<ffffffff8e71864b>] bit_wait_io+0x1b/0x60
> [<ffffffff8e718286>] __wait_on_bit_lock+0x86/0xd0
> [<ffffffff8e1acb22>] __lock_page+0x82/0xb0
> [<ffffffff8e0e9e00>] ? autoremove_wake_function+0x40/0x40
> [<ffffffff8e1ae63b>] pagecache_get_page+0x16b/0x230
> [<ffffffff8e1ca3da>] shmem_unused_huge_shrink+0x28a/0x330
> [<ffffffff8e1ca4a7>] shmem_unused_huge_scan+0x27/0x30
> [<ffffffff8e23f941>] super_cache_scan+0x181/0x190
> [<ffffffff8e1c1ab1>] shrink_slab+0x261/0x470
> [<ffffffff8e1c6588>] shrink_node+0x108/0x310
> [<ffffffff8e1c6927>] node_reclaim+0x197/0x210
> [<ffffffff8e1b5dd8>] get_page_from_freelist+0x168/0x9f0
> [<ffffffff8e1adc8e>] ? find_get_entry+0x1e/0x100
> [<ffffffff8e1ca9c5>] ? shmem_getpage_gfp+0xf5/0xbb0
> [<ffffffff8e1b77ae>] __alloc_pages_nodemask+0x10e/0x2d0
> [<ffffffff8e207d08>] alloc_pages_current+0x88/0x120
> [<ffffffff8e070287>] pte_alloc_one+0x17/0x40
> [<ffffffff8e1e117e>] __pte_alloc+0x1e/0x100
> [<ffffffff8e1e3622>] alloc_set_pte+0x4f2/0x560
> [<ffffffff8e1e3770>] do_fault+0xe0/0x620
> [<ffffffff8e1e5504>] handle_mm_fault+0x644/0xdd0
> [<ffffffff8e06a96e>] __do_page_fault+0x25e/0x4f0
> [<ffffffff8e06ac30>] do_page_fault+0x30/0x80
> [<ffffffff8e003b55>] ? do_syscall_64+0x175/0x180
> [<ffffffff8e71dae8>] page_fault+0x28/0x30
> 
> Pid 22444 didn't show up in the hung_task warning like crm_node did,
> but its /proc/pid/stack looks like so:
> 
> ~]# cat /proc/22444/stack
> [<ffffffff8e1acb22>] __lock_page+0x82/0xb0
> [<ffffffff8e1addd1>] find_lock_entry+0x61/0x80
> [<ffffffff8e1ca9c5>] shmem_getpage_gfp+0xf5/0xbb0
> [<ffffffff8e1cb9b9>] shmem_file_read_iter+0x159/0x310
> [<ffffffff8e23b2ff>] __vfs_read+0xdf/0x130
> [<ffffffff8e23ba2c>] vfs_read+0x8c/0x130
> [<ffffffff8e23cf95>] SyS_read+0x55/0xc0
> [<ffffffff8e003a47>] do_syscall_64+0x67/0x180
> [<ffffffff8e71c530>] entry_SYSCALL64_slow_path+0x25/0x25
> [<ffffffffffffffff>] 0xffffffffffffffff

I guess that /proc/sys/kernel/hung_task_warnings already became 0.
Since the default value of /proc/sys/kernel/hung_task_warnings is 10,
only first 10 warnings are shown. You can set -1 to
/proc/sys/kernel/hung_task_warnings so that all hung_task warnings
are shown.

> 
> 
> ==================== 4.14.15 ====================
> 
> On the other server running 4.14.15 the stacks look the same as you've 
> seen before.  Both full sysrq traces (30 seconds apart) are available here 
> and I made sure it includes both "Showing busy workqueues and worker 
> pools" sections:
> 
> 	https://www.linuxglobal.com/static/2018-01-28-hv2-deadlock-v4.14.15
> 
> ~]# ps -eo pid,lstart,cmd,stat |grep D
>   PID                  STARTED CMD                         STAT
> 27163 Sat Jan 27 05:15:48 2018 crm_node -N 2               D
>  1125 Sat Jan 27 14:34:40 2018 /usr/sbin/libvirtd          D
> 

crm_node was stalling at page fault for 119634 seconds (more than one day)!

----------
crm_node        D    0 27163      1 0x00000084
MemAlloc: crm_node(27163) flags=0xc00900 switches=3 seq=438 gfp=0x14200ca(GFP_HIGHUSER_MOVABLE) order=0 delay=119634513 uninterruptible
Call Trace:
 ? __schedule+0x1dc/0x770
 schedule+0x32/0x80
 io_schedule+0x12/0x40
 __lock_page+0x105/0x150
 ? page_cache_tree_insert+0xb0/0xb0
 pagecache_get_page+0x161/0x210
 shmem_unused_huge_shrink+0x334/0x3f0
 super_cache_scan+0x176/0x180
 shrink_slab+0x275/0x460
 shrink_node+0x10e/0x320
 node_reclaim+0x19d/0x250
 get_page_from_freelist+0x16a/0xac0
 ? radix_tree_lookup_slot+0x1e/0x50
 ? find_lock_entry+0x45/0x80
 ? shmem_getpage_gfp.isra.34+0xe5/0xc80
 __alloc_pages_nodemask+0x111/0x2c0
 pte_alloc_one+0x13/0x40
 __pte_alloc+0x19/0x100
 alloc_set_pte+0x468/0x4c0
 finish_fault+0x3a/0x70
 __handle_mm_fault+0x94a/0x1190
 handle_mm_fault+0xf2/0x210
 __do_page_fault+0x253/0x4d0
 do_page_fault+0x33/0x120
 ? page_fault+0x36/0x60
 page_fault+0x4c/0x60

crm_node        D    0 27163      1 0x00000084
MemAlloc: crm_node(27163) flags=0xc00900 switches=3 seq=438 gfp=0x14200ca(GFP_HIGHUSER_MOVABLE) order=0 delay=119682540 uninterruptible
Call Trace:
 ? __schedule+0x1dc/0x770
 schedule+0x32/0x80
 io_schedule+0x12/0x40
 __lock_page+0x105/0x150
 ? page_cache_tree_insert+0xb0/0xb0
 pagecache_get_page+0x161/0x210
 shmem_unused_huge_shrink+0x334/0x3f0
 super_cache_scan+0x176/0x180
 shrink_slab+0x275/0x460
 shrink_node+0x10e/0x320
 node_reclaim+0x19d/0x250
 get_page_from_freelist+0x16a/0xac0
 ? radix_tree_lookup_slot+0x1e/0x50
 ? find_lock_entry+0x45/0x80
 ? shmem_getpage_gfp.isra.34+0xe5/0xc80
 __alloc_pages_nodemask+0x111/0x2c0
 pte_alloc_one+0x13/0x40
 __pte_alloc+0x19/0x100
 alloc_set_pte+0x468/0x4c0
 finish_fault+0x3a/0x70
 __handle_mm_fault+0x94a/0x1190
 handle_mm_fault+0xf2/0x210
 __do_page_fault+0x253/0x4d0
 do_page_fault+0x33/0x120
 ? page_fault+0x36/0x60
 page_fault+0x4c/0x60
----------

And since switches= and seq= did not change, crm_node kept sleeping.

libvirtd remained stuck waiting for crm_node.
But something already went wrong more than one day ago.

----------
libvirtd        D    0  1125      1 0x00000080
Call Trace:
 ? __schedule+0x1dc/0x770
 schedule+0x32/0x80
 rwsem_down_write_failed+0x20d/0x380
 ? ida_get_new_above+0x110/0x3b0
 call_rwsem_down_write_failed+0x13/0x20
 down_write+0x29/0x40
 register_shrinker+0x45/0xa0
 sget_userns+0x468/0x4a0
 ? get_anon_bdev+0x100/0x100
 ? shmem_create+0x20/0x20
 mount_nodev+0x2a/0xa0
 mount_fs+0x34/0x150
 vfs_kern_mount+0x62/0x120
 do_mount+0x1ee/0xc50
 SyS_mount+0x7e/0xd0
 do_syscall_64+0x61/0x1a0
 entry_SYSCALL64_slow_path+0x25/0x25
----------

> I'm not sure if this is relevant, but the load average is wrong on the
> 4.14.15 machine:
>   load average: 1308.46, 1246.69, 1078.29
> There is no way those numbers are correct, top shows nothing spinning
> and vmstat only shows 1-4 processes in a running or blocked state.

If I recall correctly, insanely growing load average is a possible sign of
processes getting stuck one by one as one is created (by e.g. crond).

> 
> Here are the pid stacks in D states from ps above:
> 
> ~]# cat /proc/27163/stack 
> [<ffffffff900cd0d2>] io_schedule+0x12/0x40
> [<ffffffff901b4735>] __lock_page+0x105/0x150
> [<ffffffff901b4e61>] pagecache_get_page+0x161/0x210
> [<ffffffff901d4c74>] shmem_unused_huge_shrink+0x334/0x3f0
> [<ffffffff90251746>] super_cache_scan+0x176/0x180
> [<ffffffff901cb885>] shrink_slab+0x275/0x460
> [<ffffffff901d0d4e>] shrink_node+0x10e/0x320
> [<ffffffff901d10fd>] node_reclaim+0x19d/0x250
> [<ffffffff901be1ca>] get_page_from_freelist+0x16a/0xac0
> [<ffffffff901bef81>] __alloc_pages_nodemask+0x111/0x2c0
> [<ffffffff9006dbc3>] pte_alloc_one+0x13/0x40
> [<ffffffff901ef4e9>] __pte_alloc+0x19/0x100
> [<ffffffff901f1978>] alloc_set_pte+0x468/0x4c0
> [<ffffffff901f1a0a>] finish_fault+0x3a/0x70
> [<ffffffff901f385a>] __handle_mm_fault+0x94a/0x1190
> [<ffffffff901f4192>] handle_mm_fault+0xf2/0x210
> [<ffffffff900682a3>] __do_page_fault+0x253/0x4d0
> [<ffffffff90068553>] do_page_fault+0x33/0x120
> [<ffffffff908019dc>] page_fault+0x4c/0x60
> [<ffffffffffffffff>] 0xffffffffffffffff
> 
> 
> ~]# cat /proc/1125/stack 
> [<ffffffff907538d3>] call_rwsem_down_write_failed+0x13/0x20
> [<ffffffff901cbb45>] register_shrinker+0x45/0xa0
> [<ffffffff90251168>] sget_userns+0x468/0x4a0
> [<ffffffff9025126a>] mount_nodev+0x2a/0xa0
> [<ffffffff90251de4>] mount_fs+0x34/0x150
> [<ffffffff902703f2>] vfs_kern_mount+0x62/0x120
> [<ffffffff90272c0e>] do_mount+0x1ee/0xc50
> [<ffffffff9027397e>] SyS_mount+0x7e/0xd0
> [<ffffffff90003831>] do_syscall_64+0x61/0x1a0
> [<ffffffff9080012c>] entry_SYSCALL64_slow_path+0x25/0x25
> [<ffffffffffffffff>] 0xffffffffffffffff
> 
> > > If you have any ideas on creating an easy way to reproduce the problem, 
> > > then I can bisect---but bisecting one day at a time will take a long time, 
> > > and could be prone to bugs which I would like to avoid on this production 
> > > system.
> > > 
> > Thinking from SysRq-t output, I feel that some disk read is stuck.
> 
> Possibly.  I would not expect a hardware problem since we see this on two 
> different systems with different kernel versions.
> 
> > Since rsyslogd failed to catch portion of SysRq-t output, I can't confirm
> > whether register_shrinker() was in progress (nor all kernel worker threads
> > were reported).
> 
> As linked above, I was able to get the full trace with netconsole.
> 
> > But what I was surprised is number of kernel worker threads.
> > "grep ^kworker/ | sort" matched 314 threads and "grep ^kworker/0:"
> > matched 244.
> 
> We have many DRBD volumes and LVM volumes, most of which are dm-thin, so 
> that might be why. Also these servers have both scsi-mq and dm-mq enabled.

Ideally you could reproduce without DRBD, LVM, bcache etc. , for Marc MERLIN's
report ( http://lkml.kernel.org/r/20170502041235.zqmywvj5tiiom3jk@merlins.org )
was using (at least) bcache. It might be a bug which fails to submit I/O
request.

> > 
> > One of workqueue threads was waiting at
> > 
> > ----------
> > static void *new_read(struct dm_bufio_client *c, sector_t block,
> > 		      enum new_flag nf, struct dm_buffer **bp)
> > {
> > 	int need_submit;
> > 	struct dm_buffer *b;
> > 
> > 	LIST_HEAD(write_list);
> > 
> > 	dm_bufio_lock(c);
> > 	b = __bufio_new(c, block, nf, &need_submit, &write_list);
> > #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING
> > 	if (b && b->hold_count == 1)
> > 		buffer_record_stack(b);
> > #endif
> > 	dm_bufio_unlock(c);
> > 
> > 	__flush_write_list(&write_list);
> > 
> > 	if (!b)
> > 		return NULL;
> > 
> > 	if (need_submit)
> > 		submit_io(b, READ, read_endio);
> > 
> > 	wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE); // <= here
> > 
> > 	if (b->read_error) {
> > 		int error = blk_status_to_errno(b->read_error);
> > 
> > 		dm_bufio_release(b);
> > 
> > 		return ERR_PTR(error);
> > 	}
> > 
> > 	*bp = b;
> > 
> > 	return b->data;
> > }
> > ----------
> > 
> > but what are possible reasons? Does this request depend on workqueue availability?
> 
> We are using dm-thin which uses dm-bufio.  The dm-thin pools are working
> properly, so I don't think this is the problem---or at least if it is
> the problem, it isn't affecting the thin pool.

Some suggestions:


You can enlarge kernel printk() buffer size using log_buf_len= kernel command line
parameter. As your system is large, you could allocate e.g. log_buf_len=67108864 .
Then, you can read kernel buffer using dmesg command (e.g. /usr/bin/dmesg ).
You can add timestamp to printk() messages by doing below command.

----------
# echo Y > /sys/module/printk/parameters/time
----------


Since crm_node starts stalling rather early, you can watch out for kernel
messages and userspace messages which were printed around crm_node started
stalling, for there might be some events (e.g. error recovery) occurring.


I'm not sure but maybe page_owner gives us some clue. (Michal, what do you think?)
You can compile your kernel with CONFIG_PAGE_OWNER=y and boot your kernel with
page_owner=on kernel command line option added. But that alone does not tell on
which "struct page *" processes got stuck. We will need to call dump_page() for
reporting specific "struct page *". One of approaches would be to run a SystemTap
script shown below (in background using -F option) and check how stalling pages
has been allocated. There might be some characteristics with stalling pages.

----------
# stap -DSTP_NO_OVERLOAD=1 -F -g - << "EOF"
global waiting_pages;
probe kernel.function("__lock_page").call { waiting_pages[$__page] = gettimeofday_s(); }
probe kernel.function("__lock_page").return { delete waiting_pages[@entry($__page)]; }
function my_dump_page(page:long) %{
  dump_page((struct page *) STAP_ARG_page, "lock_page() stalling");
%}
probe timer.s(60) {
  now = gettimeofday_s();
  foreach (page in waiting_pages)
    if (now - waiting_pages[page] >= 30)
      my_dump_page(page);
}
EOF
----------

An example allocated by plain write() (though this is without stall period
because I can't reproduce your problem) is shown below.

----------
[  164.573566] page:fffff3a9024b17c0 count:4 mapcount:0 mapping:ffff8811e2876d68 index:0x5827
[  164.584758] flags: 0x1fffff800010a9(locked|waiters|uptodate|lru|private)
[  164.593678] raw: 001fffff800010a9 ffff8811e2876d68 0000000000005827 00000004ffffffff
[  164.603410] raw: fffff3a9024b17a0 fffff3a9024cc420 ffff8811e2be27b8 ffff881269fdf800
[  164.608676] page dumped because: lock_page() stalling
[  164.612558] page->mem_cgroup:ffff881269fdf800
[  164.615770] page allocated via order 0, migratetype Movable, gfp_mask 0x1c2004a(GFP_NOFS|__GFP_HIGHMEM|__GFP_HARDWALL|__GFP_MOVABLE|__GFP_WRITE)
[  164.623143]  __alloc_pages_nodemask+0x184/0x470
[  164.626939]  pagecache_get_page+0xbe/0x310
[  164.630028]  grab_cache_page_write_begin+0x1f/0x40
[  164.633436]  iomap_write_begin.constprop.15+0x5a/0x150
[  164.636013]  iomap_write_actor+0x95/0x180
[  164.637955]  iomap_apply+0xa4/0x110
[  164.639710]  iomap_file_buffered_write+0x61/0x80
[  164.641796]  xfs_file_buffered_aio_write+0xfe/0x3b0 [xfs]
[  164.643945]  xfs_file_write_iter+0xfc/0x150 [xfs]
[  164.646290]  __vfs_write+0xfc/0x170
[  164.648048]  vfs_write+0xc5/0x1b0
[  164.649760]  SyS_write+0x55/0xc0
[  164.651317]  do_syscall_64+0x66/0x210
[  164.652994]  return_from_SYSCALL_64+0x0/0x75
----------

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