Hi all,
I see 2 __might_sleep() warnings on when running LKP tests on
v3.19-rc6, one related to raid5 and another related to btrfs.
They might be exposed by this patch.
commit 8eb23b9f35aae413140d3fda766a98092c21e9b0
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
sched: Debug nested sleeps
Validate we call might_sleep() with TASK_RUNNING, which catches places
where we nest blocking primitives, eg. mutex usage in a wait loop.
Since all blocking is arranged through task_struct::state, nesting
this will cause the inner primitive to set TASK_RUNNING and the outer
will thus not block.
Another observed problem is calling a blocking function from
schedule()->sched_submit_work()->blk_schedule_flush_plug() which will
then destroy the task state for the actual __schedule() call that
comes after it.
dmesg-ivb44:20150129001242:x86_64-rhel:3.19.0-rc6-g26bc420b:1
FSUse% Count Size Files/sec App Overhead
[ 60.691525] ------------[ cut here ]------------
[ 60.697499] WARNING: CPU: 0 PID: 1065 at kernel/sched/core.c:7300 __might_sleep+0xbd/0xd0()
[ 60.709010] do not call blocking ops when !TASK_RUNNING; state=2 set at [<ffffffff810b63ff>] prepare_to_wait+0x2f/0x90
[ 60.721646] Modules linked in: f2fs raid456 async_raid6_recov async_memcpy async_pq async_xor xor async_tx raid6_pq ipmi_watchdog netconsole sg sd_mod mgag200 syscopyarea sysfillrect isci sysimgblt libsas ttm snd_pcm ahci snd_timer drm_kms_helper scsi_transport_sas libahci snd sb_edac soundcore drm libata edac_core i2c_i801 pcspkr wmi ipmi_si ipmi_msghandler
[ 60.759585] CPU: 0 PID: 1065 Comm: kworker/u481:6 Not tainted 3.19.0-rc6-g26bc420b #1
[ 60.769025] Hardware name: Intel Corporation S2600WP/S2600WP, BIOS SE5C600.86B.02.02.0002.122320131210 12/23/2013
[ 60.781193] Workqueue: writeback bdi_writeback_workfn (flush-9:0)
[ 60.788725] ffffffff81b75d50 ffff88080979b3e8 ffffffff818a38f0 ffff88081ee100f8
[ 60.797820] ffff88080979b438 ffff88080979b428 ffffffff8107260a ffff88080979b428
[ 60.806879] ffffffff81b8c759 00000000000004d9 0000000000000000 0000000063fbe018
[ 60.815935] Call Trace:
[ 60.819368] [<ffffffff818a38f0>] dump_stack+0x4c/0x65
[ 60.825817] [<ffffffff8107260a>] warn_slowpath_common+0x8a/0xc0
[ 60.833269] [<ffffffff81072686>] warn_slowpath_fmt+0x46/0x50
[ 60.840379] [<ffffffff810afe95>] ? pick_next_task_fair+0x1b5/0x8d0
[ 60.848104] [<ffffffff810b63ff>] ? prepare_to_wait+0x2f/0x90
[ 60.855215] [<ffffffff810b63ff>] ? prepare_to_wait+0x2f/0x90
[ 60.862337] [<ffffffff8109874d>] __might_sleep+0xbd/0xd0
[ 60.869044] [<ffffffff811c7cd7>] kmem_cache_alloc_trace+0x1d7/0x250
[ 60.876830] [<ffffffff817175d7>] ? bitmap_get_counter+0x117/0x280
[ 60.884429] [<ffffffff817175d7>] bitmap_get_counter+0x117/0x280
[ 60.891807] [<ffffffff810f6d02>] ? __module_text_address+0x12/0x70
[ 60.899452] [<ffffffff81717f54>] bitmap_startwrite+0x74/0x300
[ 60.906601] [<ffffffffa017659a>] add_stripe_bio+0x2aa/0x350 [raid456]
[ 60.914518] [<ffffffffa017d20d>] make_request+0x1dd/0xf30 [raid456]
[ 60.922211] [<ffffffff818aae00>] ? __account_scheduler_latency+0x150/0x370
[ 60.930581] [<ffffffff810b67e0>] ? wait_woken+0xc0/0xc0
[ 60.937100] [<ffffffff8109201f>] ? kthread+0xef/0x110
[ 60.943404] [<ffffffff8170b8c4>] md_make_request+0xf4/0x190
[ 60.950277] [<ffffffff8140fa3d>] ? radix_tree_lookup+0xd/0x10
[ 60.957392] [<ffffffffa027829c>] ? get_node_info+0x8c/0x2b0 [f2fs]
[ 60.964937] [<ffffffff813db848>] generic_make_request+0xd8/0x130
[ 60.972291] [<ffffffff813db908>] submit_bio+0x68/0x160
[ 60.978677] [<ffffffffa0273d58>] __submit_merged_bio+0x48/0x110 [f2fs]
[ 60.986622] [<ffffffffa0274b48>] f2fs_submit_page_mbio+0xa8/0x1f0 [f2fs]
[ 60.994817] [<ffffffffa027f7c0>] write_data_page+0x90/0xc0 [f2fs]
[ 61.002272] [<ffffffffa0276adf>] do_write_data_page+0xdf/0x310 [f2fs]
[ 61.010119] [<ffffffffa0276ee6>] f2fs_write_data_page+0x1d6/0x3e0 [f2fs]
[ 61.018275] [<ffffffffa0273e37>] __f2fs_writepage+0x17/0x50 [f2fs]
[ 61.025831] [<ffffffff811758cc>] write_cache_pages+0x21c/0x4e0
[ 61.033003] [<ffffffff813db848>] ? generic_make_request+0xd8/0x130
[ 61.040543] [<ffffffffa0273e20>] ? __submit_merged_bio+0x110/0x110 [f2fs]
[ 61.048843] [<ffffffffa027481c>] f2fs_write_data_pages+0xac/0x200 [f2fs]
[ 61.056969] [<ffffffff8117777e>] do_writepages+0x1e/0x30
[ 61.063506] [<ffffffff812108f0>] __writeback_single_inode+0x40/0x280
[ 61.071217] [<ffffffff810b6385>] ? wake_up_bit+0x25/0x30
[ 61.077763] [<ffffffff81211b03>] writeback_sb_inodes+0x263/0x410
[ 61.085114] [<ffffffff81211d4f>] __writeback_inodes_wb+0x9f/0xd0
[ 61.092423] [<ffffffff8121220b>] wb_writeback+0x24b/0x300
[ 61.099030] [<ffffffff81214194>] bdi_writeback_workfn+0x1d4/0x470
[ 61.106400] [<ffffffff8108bcc8>] process_one_work+0x158/0x4b0
[ 61.113383] [<ffffffff8108c08b>] worker_thread+0x6b/0x5e0
[ 61.119967] [<ffffffff8108c020>] ? process_one_work+0x4b0/0x4b0
[ 61.127117] [<ffffffff8109201f>] kthread+0xef/0x110
[ 61.133102] [<ffffffff81091f30>] ? kthread_create_on_node+0x180/0x180
[ 61.140805] [<ffffffff818abf7c>] ret_from_fork+0x7c/0xb0
[ 61.147269] [<ffffffff81091f30>] ? kthread_create_on_node+0x180/0x180
[ 61.154973] ---[ end trace 2db29906e8050768 ]---
17 51200 4194304 32.0 2701319
dmesg-lkp-ne04:20150128110549:x86_64-rhel:3.19.0-rc6-g26bc420b:1
FSUse% Count Size Files/sec App Overhead
[ 101.678419] ------------[ cut here ]------------
[ 101.684612] WARNING: CPU: 4 PID: 2153 at kernel/sched/core.c:7300 __might_sleep+0xbd/0xd0()
[ 101.696412] do not call blocking ops when !TASK_RUNNING; state=2 set at [<ffffffff810b63ff>] prepare_to_wait+0x2f/0x90
[ 101.709259] Modules linked in: ipmi_watchdog btrfs sr_mod cdrom xor raid6_pq sg sd_mod snd_pcm snd_timer snd soundcore pcspkr mgag200 syscopyarea sysfillrect sysimgblt ttm ahci drm_kms_helper libahci drm libata usb_storage i2c_i801 ipmi_si ipmi_msghandler i7core_edac edac_core acpi_cpufreq
[ 101.741823] CPU: 4 PID: 2153 Comm: fs_mark Not tainted 3.19.0-rc6-g26bc420b #1
[ 101.750851] Hardware name: Intel Corporation S5520UR/S5520UR, BIOS S5500.86B.01.00.0050.050620101605 05/06/2010
[ 101.763101] ffffffff81b75d50 ffff8801dd947c78 ffffffff818a38f0 ffff8801e9c500f8
[ 101.772473] ffff8801dd947cc8 ffff8801dd947cb8 ffffffff8107260a 0000000000000004
[ 101.781793] ffffffff81b76780 0000000000000061 0000000000000000 ffff8801e8438000
[ 101.791140] Call Trace:
[ 101.794751] [<ffffffff818a38f0>] dump_stack+0x4c/0x65
[ 101.801386] [<ffffffff8107260a>] warn_slowpath_common+0x8a/0xc0
[ 101.809003] [<ffffffff81072686>] warn_slowpath_fmt+0x46/0x50
[ 101.816335] [<ffffffff810b63ff>] ? prepare_to_wait+0x2f/0x90
[ 101.823616] [<ffffffff810b63ff>] ? prepare_to_wait+0x2f/0x90
[ 101.830875] [<ffffffff8109874d>] __might_sleep+0xbd/0xd0
[ 101.837766] [<ffffffff818a9364>] mutex_lock+0x24/0x50
[ 101.844399] [<ffffffffa0285e88>] wait_for_writer+0x68/0xc0 [btrfs]
[ 101.853029] [<ffffffff810b67e0>] ? wait_woken+0xc0/0xc0
[ 101.859849] [<ffffffffa028b918>] btrfs_sync_log+0xf8/0xa70 [btrfs]
[ 101.867740] [<ffffffffa028c7bd>] ? btrfs_log_dentry_safe+0x6d/0x80 [btrfs]
[ 101.876395] [<ffffffffa02605d2>] btrfs_sync_file+0x2f2/0x330 [btrfs]
[ 101.884375] [<ffffffff81218101>] do_fsync+0x51/0x80
[ 101.890737] [<ffffffff81197977>] ? might_fault+0x47/0x50
[ 101.897610] [<ffffffff812183a0>] SyS_fsync+0x10/0x20
[ 101.904096] [<ffffffff818ac029>] system_call_fastpath+0x12/0x17
[ 101.911647] ---[ end trace 77681997f1c4e23f ]---
1 51200 8192 365.3 2076332
Thanks,
Fengguang
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