• Shaohua Li's avatar
    sched: always use blk_schedule_flush_plug in io_schedule_out · 5596d0d5
    Shaohua Li authored
    block plug callback could sleep, so we introduce a parameter
    'from_schedule' and corresponding drivers can use it to destinguish a
    schedule plug flush or a plug finish. Unfortunately io_schedule_out
    still uses blk_flush_plug(). This causes below output (Note, I added a
    might_sleep() in raid1_unplug to make it trigger faster, but the whole
    thing doesn't matter if I add might_sleep). In raid1/10, this can cause
    deadlock.
    
    This patch makes io_schedule_out always uses blk_schedule_flush_plug.
    This should only impact drivers (as far as I know, raid 1/10) which are
    sensitive to the 'from_schedule' parameter.
    
    [  370.817949] ------------[ cut here ]------------
    [  370.817960] WARNING: CPU: 7 PID: 145 at ../kernel/sched/core.c:7306 __might_sleep+0x7f/0x90()
    [  370.817969] do not call blocking ops when !TASK_RUNNING; state=2 set at [<ffffffff81092fcf>] prepare_to_wait+0x2f/0x90
    [  370.817971] Modules linked in: raid1
    [  370.817976] CPU: 7 PID: 145 Comm: kworker/u16:9 Tainted: G        W       4.0.0+ #361
    [  370.817977] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140709_153802- 04/01/2014
    [  370.817983] Workqueue: writeback bdi_writeback_workfn (flush-9:1)
    [  370.817985]  ffffffff81cd83be ffff8800ba8cb298 ffffffff819dd7af 0000000000000001
    [  370.817988]  ffff8800ba8cb2e8 ffff8800ba8cb2d8 ffffffff81051afc ffff8800ba8cb2c8
    [  370.817990]  ffffffffa00061a8 000000000000041e 0000000000000000 ffff8800ba8cba28
    [  370.817993] Call Trace:
    [  370.817999]  [<ffffffff819dd7af>] dump_stack+0x4f/0x7b
    [  370.818002]  [<ffffffff81051afc>] warn_slowpath_common+0x8c/0xd0
    [  370.818004]  [<ffffffff81051b86>] warn_slowpath_fmt+0x46/0x50
    [  370.818006]  [<ffffffff81092fcf>] ? prepare_to_wait+0x2f/0x90
    [  370.818008]  [<ffffffff81092fcf>] ? prepare_to_wait+0x2f/0x90
    [  370.818010]  [<ffffffff810776ef>] __might_sleep+0x7f/0x90
    [  370.818014]  [<ffffffffa0000c03>] raid1_unplug+0xd3/0x170 [raid1]
    [  370.818024]  [<ffffffff81421d9a>] blk_flush_plug_list+0x8a/0x1e0
    [  370.818028]  [<ffffffff819e3550>] ? bit_wait+0x50/0x50
    [  370.818031]  [<ffffffff819e21b0>] io_schedule_timeout+0x130/0x140
    [  370.818033]  [<ffffffff819e3586>] bit_wait_io+0x36/0x50
    [  370.818034]  [<ffffffff819e31b5>] __wait_on_bit+0x65/0x90
    [  370.818041]  [<ffffffff8125b67c>] ? ext4_read_block_bitmap_nowait+0xbc/0x630
    [  370.818043]  [<ffffffff819e3550>] ? bit_wait+0x50/0x50
    [  370.818045]  [<ffffffff819e3302>] out_of_line_wait_on_bit+0x72/0x80
    [  370.818047]  [<ffffffff810935e0>] ? autoremove_wake_function+0x40/0x40
    [  370.818050]  [<ffffffff811de744>] __wait_on_buffer+0x44/0x50
    [  370.818053]  [<ffffffff8125ae80>] ext4_wait_block_bitmap+0xe0/0xf0
    [  370.818058]  [<ffffffff812975d6>] ext4_mb_init_cache+0x206/0x790
    [  370.818062]  [<ffffffff8114bc6c>] ? lru_cache_add+0x1c/0x50
    [  370.818064]  [<ffffffff81297c7e>] ext4_mb_init_group+0x11e/0x200
    [  370.818066]  [<ffffffff81298231>] ext4_mb_load_buddy+0x341/0x360
    [  370.818068]  [<ffffffff8129a1a3>] ext4_mb_find_by_goal+0x93/0x2f0
    [  370.818070]  [<ffffffff81295b54>] ? ext4_mb_normalize_request+0x1e4/0x5b0
    [  370.818072]  [<ffffffff8129ab67>] ext4_mb_regular_allocator+0x67/0x460
    [  370.818074]  [<ffffffff81295b54>] ? ext4_mb_normalize_request+0x1e4/0x5b0
    [  370.818076]  [<ffffffff8129ca4b>] ext4_mb_new_blocks+0x4cb/0x620
    [  370.818079]  [<ffffffff81290956>] ext4_ext_map_blocks+0x4c6/0x14d0
    [  370.818081]  [<ffffffff812a4d4e>] ? ext4_es_lookup_extent+0x4e/0x290
    [  370.818085]  [<ffffffff8126399d>] ext4_map_blocks+0x14d/0x4f0
    [  370.818088]  [<ffffffff81266fbd>] ext4_writepages+0x76d/0xe50
    [  370.818094]  [<ffffffff81149691>] do_writepages+0x21/0x50
    [  370.818097]  [<ffffffff811d5c00>] __writeback_single_inode+0x60/0x490
    [  370.818099]  [<ffffffff811d630a>] writeback_sb_inodes+0x2da/0x590
    [  370.818103]  [<ffffffff811abf4b>] ? trylock_super+0x1b/0x50
    [  370.818105]  [<ffffffff811abf4b>] ? trylock_super+0x1b/0x50
    [  370.818107]  [<ffffffff811d665f>] __writeback_inodes_wb+0x9f/0xd0
    [  370.818109]  [<ffffffff811d69db>] wb_writeback+0x34b/0x3c0
    [  370.818111]  [<ffffffff811d70df>] bdi_writeback_workfn+0x23f/0x550
    [  370.818116]  [<ffffffff8106bbd8>] process_one_work+0x1c8/0x570
    [  370.818117]  [<ffffffff8106bb5b>] ? process_one_work+0x14b/0x570
    [  370.818119]  [<ffffffff8106c09b>] worker_thread+0x11b/0x470
    [  370.818121]  [<ffffffff8106bf80>] ? process_one_work+0x570/0x570
    [  370.818124]  [<ffffffff81071868>] kthread+0xf8/0x110
    [  370.818126]  [<ffffffff81071770>] ? kthread_create_on_node+0x210/0x210
    [  370.818129]  [<ffffffff819e9322>] ret_from_fork+0x42/0x70
    [  370.818131]  [<ffffffff81071770>] ? kthread_create_on_node+0x210/0x210
    [  370.818132] ---[ end trace 7b4deb71e68b6605 ]---
    
    V2: don't change ->in_iowait
    
    Cc: NeilBrown <neilb@suse.de>
    Signed-off-by: default avatarShaohua Li <shli@fb.com>
    Reviewed-by: default avatarJeff Moyer <jmoyer@redhat.com>
    Signed-off-by: default avatarJens Axboe <axboe@fb.com>
    5596d0d5
core.c 200 KB