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Date: Tue, 16 Jun 2015 22:14:36 +0900
From: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To: Minchan Kim <minchan@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org,
Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Subject: [RFC] zram/zcomp: lockdep inconsistent lock state
Hello,
Ran into this one today on one of my x86_64 machines.
[ 747.233715] =================================
[ 747.233717] [ INFO: inconsistent lock state ]
[ 747.233719] 4.1.0-rc7-next-20150615-dbg-00016-g8bdf555-dirty #211 Not tainted
[ 747.233720] ---------------------------------
[ 747.233722] inconsistent {IN-RECLAIM_FS-W} -> {RECLAIM_FS-ON-W} usage.
[ 747.233724] git/20158 [HC0[0]:SC0[0]:HE1:SE1] takes:
[ 747.233725] (jbd2_handle){+.+.?.}, at: [<ffffffff811e31db>] start_this_handle+0x4ca/0x555
[ 747.233733] {IN-RECLAIM_FS-W} state was registered at:
[ 747.233735] [<ffffffff8107b8e9>] __lock_acquire+0x8da/0x117b
[ 747.233738] [<ffffffff8107c950>] lock_acquire+0x10c/0x1a7
[ 747.233740] [<ffffffff811e323e>] start_this_handle+0x52d/0x555
[ 747.233742] [<ffffffff811e331a>] jbd2__journal_start+0xb4/0x237
[ 747.233744] [<ffffffff811cc6c7>] __ext4_journal_start_sb+0x108/0x17e
[ 747.233748] [<ffffffff811a90bf>] ext4_dirty_inode+0x32/0x61
[ 747.233750] [<ffffffff8115f37e>] __mark_inode_dirty+0x16b/0x60c
[ 747.233754] [<ffffffff81150ad6>] iput+0x11e/0x274
[ 747.233757] [<ffffffff8114bfbd>] __dentry_kill+0x148/0x1b8
[ 747.233759] [<ffffffff8114c9d9>] shrink_dentry_list+0x274/0x44a
[ 747.233761] [<ffffffff8114d38a>] prune_dcache_sb+0x4a/0x55
[ 747.233763] [<ffffffff8113b1ad>] super_cache_scan+0xfc/0x176
[ 747.233767] [<ffffffff810fa089>] shrink_slab.part.14.constprop.25+0x2a2/0x4d3
[ 747.233770] [<ffffffff810fcccb>] shrink_zone+0x74/0x140
[ 747.233772] [<ffffffff810fd924>] kswapd+0x6b7/0x930
[ 747.233774] [<ffffffff81058887>] kthread+0x107/0x10f
[ 747.233778] [<ffffffff814fadff>] ret_from_fork+0x3f/0x70
[ 747.233783] irq event stamp: 138297
[ 747.233784] hardirqs last enabled at (138297): [<ffffffff8107aff3>] debug_check_no_locks_freed+0x113/0x12f
[ 747.233786] hardirqs last disabled at (138296): [<ffffffff8107af13>] debug_check_no_locks_freed+0x33/0x12f
[ 747.233788] softirqs last enabled at (137818): [<ffffffff81040f89>] __do_softirq+0x2d3/0x3e9
[ 747.233792] softirqs last disabled at (137813): [<ffffffff81041292>] irq_exit+0x41/0x95
[ 747.233794]
other info that might help us debug this:
[ 747.233796] Possible unsafe locking scenario:
[ 747.233797] CPU0
[ 747.233798] ----
[ 747.233799] lock(jbd2_handle);
[ 747.233801] <Interrupt>
[ 747.233801] lock(jbd2_handle);
[ 747.233803]
*** DEADLOCK ***
[ 747.233805] 5 locks held by git/20158:
[ 747.233806] #0: (sb_writers#7){.+.+.+}, at: [<ffffffff81155411>] mnt_want_write+0x24/0x4b
[ 747.233811] #1: (&type->i_mutex_dir_key#2/1){+.+.+.}, at: [<ffffffff81145087>] lock_rename+0xd9/0xe3
[ 747.233817] #2: (&sb->s_type->i_mutex_key#11){+.+.+.}, at: [<ffffffff8114f8e2>] lock_two_nondirectories+0x3f/0x6b
[ 747.233822] #3: (&sb->s_type->i_mutex_key#11/4){+.+.+.}, at: [<ffffffff8114f909>] lock_two_nondirectories+0x66/0x6b
[ 747.233827] #4: (jbd2_handle){+.+.?.}, at: [<ffffffff811e31db>] start_this_handle+0x4ca/0x555
[ 747.233831]
stack backtrace:
[ 747.233834] CPU: 2 PID: 20158 Comm: git Not tainted 4.1.0-rc7-next-20150615-dbg-00016-g8bdf555-dirty #211
[ 747.233837] ffff8800a56cea40 ffff88010d0a75f8 ffffffff814f446d ffffffff81077036
[ 747.233840] ffffffff823a84b0 ffff88010d0a7638 ffffffff814f3849 0000000000000001
[ 747.233843] 000000000000000a ffff8800a56cf6f8 ffff8800a56cea40 ffffffff810795dd
[ 747.233846] Call Trace:
[ 747.233849] [<ffffffff814f446d>] dump_stack+0x4c/0x6e
[ 747.233852] [<ffffffff81077036>] ? up+0x39/0x3e
[ 747.233854] [<ffffffff814f3849>] print_usage_bug.part.23+0x25b/0x26a
[ 747.233857] [<ffffffff810795dd>] ? print_shortest_lock_dependencies+0x182/0x182
[ 747.233859] [<ffffffff8107a9c9>] mark_lock+0x384/0x56d
[ 747.233862] [<ffffffff8107ac11>] mark_held_locks+0x5f/0x76
[ 747.233865] [<ffffffffa023d2f3>] ? zcomp_strm_alloc+0x25/0x73 [zram]
[ 747.233867] [<ffffffff8107d13b>] lockdep_trace_alloc+0xb2/0xb5
[ 747.233870] [<ffffffff8112bac7>] kmem_cache_alloc_trace+0x32/0x1e2
[ 747.233873] [<ffffffffa023d2f3>] zcomp_strm_alloc+0x25/0x73 [zram]
[ 747.233876] [<ffffffffa023d428>] zcomp_strm_multi_find+0xe7/0x173 [zram]
[ 747.233879] [<ffffffffa023d58b>] zcomp_strm_find+0xc/0xe [zram]
[ 747.233881] [<ffffffffa023f292>] zram_bvec_rw+0x2ca/0x7e0 [zram]
[ 747.233885] [<ffffffffa023fa8c>] zram_make_request+0x1fa/0x301 [zram]
[ 747.233889] [<ffffffff812142f8>] generic_make_request+0x9c/0xdb
[ 747.233891] [<ffffffff8121442e>] submit_bio+0xf7/0x120
[ 747.233895] [<ffffffff810f1c0c>] ? __test_set_page_writeback+0x1a0/0x1b8
[ 747.233897] [<ffffffff811a9d00>] ext4_io_submit+0x2e/0x43
[ 747.233899] [<ffffffff811a9efa>] ext4_bio_write_page+0x1b7/0x300
[ 747.233902] [<ffffffff811a2106>] mpage_submit_page+0x60/0x77
[ 747.233905] [<ffffffff811a25b0>] mpage_map_and_submit_buffers+0x10f/0x21d
[ 747.233907] [<ffffffff811a6814>] ext4_writepages+0xc8c/0xe1b
[ 747.233910] [<ffffffff810f3f77>] do_writepages+0x23/0x2c
[ 747.233913] [<ffffffff810ea5d1>] __filemap_fdatawrite_range+0x84/0x8b
[ 747.233915] [<ffffffff810ea657>] filemap_flush+0x1c/0x1e
[ 747.233917] [<ffffffff811a3851>] ext4_alloc_da_blocks+0xb8/0x117
[ 747.233919] [<ffffffff811af52a>] ext4_rename+0x132/0x6dc
[ 747.233921] [<ffffffff8107ac11>] ? mark_held_locks+0x5f/0x76
[ 747.233924] [<ffffffff811afafd>] ext4_rename2+0x29/0x2b
[ 747.233926] [<ffffffff811427ea>] vfs_rename+0x540/0x636
[ 747.233928] [<ffffffff81146a01>] SyS_renameat2+0x359/0x44d
[ 747.233931] [<ffffffff81146b26>] SyS_rename+0x1e/0x20
[ 747.233933] [<ffffffff814faa17>] entry_SYSCALL_64_fastpath+0x12/0x6f
zcomp has been around for quite some time (more than one year), so I
still need to understand what has changed and now causing lockdep splat.
I didn't have enought time to analyze it yet.
Removing FS bit from allocation flags most likely will make lockdep happy
(will test it tomorrow). It seems that zram write path can be triggered
from the shrinker; and inconsistency in the fact that we may do __GFP_FS
allocations from both regular writes and from writes issued by the shrinker.
If zcomp is now incorrect, then I can think of two options:
-- use GFP_NOFS
-- change zcomp allocation model from on-demand allocation (from write path)
to pre-allocated one (allocate the required number of backends in
zcomp_set_max_streams()).
untested, quick and dirty.
==================================================================================================
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
---
drivers/block/zram/zcomp.c | 4 ++--
drivers/block/zram/zcomp_lz4.c | 2 +-
drivers/block/zram/zcomp_lzo.c | 2 +-
3 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
index 965d1af..9107084 100644
--- a/drivers/block/zram/zcomp.c
+++ b/drivers/block/zram/zcomp.c
@@ -76,7 +76,7 @@ static void zcomp_strm_free(struct zcomp *comp, struct zcomp_strm *zstrm)
*/
static struct zcomp_strm *zcomp_strm_alloc(struct zcomp *comp)
{
- struct zcomp_strm *zstrm = kmalloc(sizeof(*zstrm), GFP_KERNEL);
+ struct zcomp_strm *zstrm = kmalloc(sizeof(*zstrm), GFP_NOFS);
if (!zstrm)
return NULL;
@@ -85,7 +85,7 @@ static struct zcomp_strm *zcomp_strm_alloc(struct zcomp *comp)
* allocate 2 pages. 1 for compressed data, plus 1 extra for the
* case when compressed size is larger than the original one
*/
- zstrm->buffer = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
+ zstrm->buffer = (void *)__get_free_pages(GFP_NOFS | __GFP_ZERO, 1);
if (!zstrm->private || !zstrm->buffer) {
zcomp_strm_free(comp, zstrm);
zstrm = NULL;
diff --git a/drivers/block/zram/zcomp_lz4.c b/drivers/block/zram/zcomp_lz4.c
index f2afb7e..975419e 100644
--- a/drivers/block/zram/zcomp_lz4.c
+++ b/drivers/block/zram/zcomp_lz4.c
@@ -15,7 +15,7 @@
static void *zcomp_lz4_create(void)
{
- return kzalloc(LZ4_MEM_COMPRESS, GFP_KERNEL);
+ return kzalloc(LZ4_MEM_COMPRESS, GFP_NOFS);
}
static void zcomp_lz4_destroy(void *private)
diff --git a/drivers/block/zram/zcomp_lzo.c b/drivers/block/zram/zcomp_lzo.c
index da1bc47..0009f93 100644
--- a/drivers/block/zram/zcomp_lzo.c
+++ b/drivers/block/zram/zcomp_lzo.c
@@ -15,7 +15,7 @@
static void *lzo_create(void)
{
- return kzalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
+ return kzalloc(LZO1X_MEM_COMPRESS, GFP_NOFS);
}
static void lzo_destroy(void *private)
--
2.4.3.413.ga5fe668
--
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