kmem_alloc hang in xlog_cil_insert_format_items

[juncheng bai <baijuncheng@unitedstack.com>]

Hi, ALL

Today, I test xfs to verify kmem_alloc hang in xfs_dir2_block_to_sf
in kernel-3.14.

My test case:
I use three ssd disks to build three xfs filesystems.
My mount options:
rw,noexec,nodev,noatime,nodiratime,barrier=0,discard,inode64,logbsize=256k,delaylog

Each xfs filesystem run a postmark and two fio.

postmark parameter:
set size 100000 100000000
set location /var/xfs-0/
set seed 900
set number 100000
set subdirectories 5000
set read 40960 65536000
set write 40960 65536000
set transactions 10000
set bias create 40
set bias read 60
run xfs-0-result.txt
show

fio parameter:
fio -directory /var/${1} -rw=randrw -ioengine=libaio -iodepth=128 
-size=128M -name=stress_test -numjobs=256

After five hours, the output of warning from xfs:
2015-07-07T23:32:18.230120+00:00 server-69 kernel: XFS: possible memory 
allocation deadlock in kmem_alloc (mode:0x8250 size:32832)
2015-07-07T23:32:18.230131+00:00 server-69 kernel: CPU: 1 PID: 15954 
Comm: postmark Tainted: G O 3.12.21-1.el6.x86_64 #1
2015-07-07T23:32:18.230134+00:00 server-69 kernel: Hardware name: Dell 
Inc. PowerEdge R630/0CNCJW, BIOS 1.2.10 03/09/2015
2015-07-07T23:32:18.230147+00:00 server-69 kernel: 0000000000000000 
ffff880481c99bb8 ffffffff8162562a 0000000000008040
2015-07-07T23:32:18.230148+00:00 server-69 kernel: 000000000000044c 
ffff880481c99bf8 ffffffffa06c457c ffff880481c99bf8
2015-07-07T23:32:18.230149+00:00 server-69 kernel: ffff88086936bcf0 
ffff8804a17ecd00 ffff880066a48000 ffff880044158000
2015-07-07T23:32:18.230150+00:00 server-69 kernel: Call Trace:
2015-07-07T23:32:18.230152+00:00 server-69 kernel: [<ffffffff8162562a>] 
dump_stack+0x49/0x5f
2015-07-07T23:32:18.230153+00:00 server-69 kernel: [<ffffffffa06c457c>] 
kmem_alloc+0xec/0x100 [xfs]
2015-07-07T23:32:18.230186+00:00 server-69 kernel: [<ffffffffa0709b6f>] 
xlog_cil_insert_format_items+0x11f/0x1f0 [xfs]
2015-07-07T23:32:18.230205+00:00 server-69 kernel: [<ffffffffa06d0d00>] 
? xfs_bmap_last_offset+0x30/0xc0 [xfs]
2015-07-07T23:32:18.230211+00:00 server-69 kernel: [<ffffffffa0709d8d>] 
xlog_cil_insert_items+0x3d/0x1b0 [xfs]
2015-07-07T23:32:18.230212+00:00 server-69 kernel: [<ffffffffa070a484>] 
xfs_log_commit_cil+0x54/0x150 [xfs]
2015-07-07T23:32:18.230228+00:00 server-69 kernel: [<ffffffffa06c3cb9>] 
xfs_trans_commit+0x79/0x270 [xfs]
2015-07-07T23:32:18.230230+00:00 server-69 kernel: [<ffffffffa06f78c2>] 
xfs_remove+0x2d2/0x350 [xfs]
2015-07-07T23:32:18.230235+00:00 server-69 kernel: [<ffffffff811c882f>] 
? d_walk+0x5f/0x260
2015-07-07T23:32:18.230236+00:00 server-69 kernel: [<ffffffffa06b9782>] 
xfs_vn_unlink+0x52/0xa0 [xfs]
2015-07-07T23:32:18.230237+00:00 server-69 kernel: [<ffffffff811be22b>] 
vfs_rmdir+0xbb/0x110
2015-07-07T23:32:18.230238+00:00 server-69 kernel: [<ffffffff811c14a3>] 
do_rmdir+0x203/0x220
2015-07-07T23:32:18.230239+00:00 server-69 kernel: [<ffffffff811c1516>] 
SyS_rmdir+0x16/0x20
2015-07-07T23:32:18.230240+00:00 server-69 kernel: [<ffffffff81632729>] 
system_call_fastpath+0x16/0x1b

In function, I add code to get more info:
57c57
< 		if (!(++retries % 100))
---
 > 		if (!(++retries % 100)) {
59,60c59,62
< 		"possible memory allocation deadlock in %s (mode:0x%x)",
< 					__func__, lflags);
---
 > 		"possible memory allocation deadlock in %s (mode:0x%x, size:%zu)",
 > 					__func__, lflags, size);
 > 			dump_stack();
 > 		}

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