From: Nikolay Borisov <nborisov@xxxxxxxx>
Subject: lockdep: teach lockdep about memalloc_noio_save
Patch series "scope GFP_NOFS api", v5.
This patch (of 7):
Commit 21caf2fc1931 ("mm: teach mm by current context info to not do I/O
during memory allocation") added the memalloc_noio_(save|restore)
functions to enable people to modify the MM behavior by disabling I/O
during memory allocation. This was further extended in Fixes:
934f3072c17c ("mm: clear __GFP_FS when PF_MEMALLOC_NOIO is set").
memalloc_noio_* functions prevent allocation paths recursing back into the
filesystem without explicitly changing the flags for every allocation
site. However, lockdep hasn't been keeping up with the changes and it
entirely misses handling the memalloc_noio adjustments. Instead, it is
left to the callers of __lockdep_trace_alloc to call the function after
they have shaven the respective GFP flags which can lead to false
positives:
[ 644.173373] =================================
[ 644.174012] [ INFO: inconsistent lock state ]
[ 644.174012] 4.10.0-nbor #134 Not tainted
[ 644.174012] ---------------------------------
[ 644.174012] inconsistent {IN-RECLAIM_FS-W} -> {RECLAIM_FS-ON-W} usage.
[ 644.174012] fsstress/3365 [HC0[0]:SC0[0]:HE1:SE1] takes:
[ 644.174012] (&xfs_nondir_ilock_class){++++?.}, at: [<ffffffff8136f231>] xfs_ilock+0x141/0x230
[ 644.174012] {IN-RECLAIM_FS-W} state was registered at:
[ 644.174012] __lock_acquire+0x62a/0x17c0
[ 644.174012] lock_acquire+0xc5/0x220
[ 644.174012] down_write_nested+0x4f/0x90
[ 644.174012] xfs_ilock+0x141/0x230
[ 644.174012] xfs_reclaim_inode+0x12a/0x320
[ 644.174012] xfs_reclaim_inodes_ag+0x2c8/0x4e0
[ 644.174012] xfs_reclaim_inodes_nr+0x33/0x40
[ 644.174012] xfs_fs_free_cached_objects+0x19/0x20
[ 644.174012] super_cache_scan+0x191/0x1a0
[ 644.174012] shrink_slab+0x26f/0x5f0
[ 644.174012] shrink_node+0xf9/0x2f0
[ 644.174012] kswapd+0x356/0x920
[ 644.174012] kthread+0x10c/0x140
[ 644.174012] ret_from_fork+0x31/0x40
[ 644.174012] irq event stamp: 173777
[ 644.174012] hardirqs last enabled at (173777): [<ffffffff8105b440>] __local_bh_enable_ip+0x70/0xc0
[ 644.174012] hardirqs last disabled at (173775): [<ffffffff8105b407>] __local_bh_enable_ip+0x37/0xc0
[ 644.174012] softirqs last enabled at (173776): [<ffffffff81357e2a>] _xfs_buf_find+0x67a/0xb70
[ 644.174012] softirqs last disabled at (173774): [<ffffffff81357d8b>] _xfs_buf_find+0x5db/0xb70
[ 644.174012]
[ 644.174012] other info that might help us debug this:
[ 644.174012] Possible unsafe locking scenario:
[ 644.174012]
[ 644.174012] CPU0
[ 644.174012] ----
[ 644.174012] lock(&xfs_nondir_ilock_class);
[ 644.174012] <Interrupt>
[ 644.174012] lock(&xfs_nondir_ilock_class);
[ 644.174012]
[ 644.174012] *** DEADLOCK ***
[ 644.174012]
[ 644.174012] 4 locks held by fsstress/3365:
[ 644.174012] #0: (sb_writers#10){++++++}, at: [<ffffffff81208d04>] mnt_want_write+0x24/0x50
[ 644.174012] #1: (&sb->s_type->i_mutex_key#12){++++++}, at: [<ffffffff8120ea2f>] vfs_setxattr+0x6f/0xb0
[ 644.174012] #2: (sb_internal#2){++++++}, at: [<ffffffff8138185c>] xfs_trans_alloc+0xfc/0x140
[ 644.174012] #3: (&xfs_nondir_ilock_class){++++?.}, at: [<ffffffff8136f231>] xfs_ilock+0x141/0x230
[ 644.174012]
[ 644.174012] stack backtrace:
[ 644.174012] CPU: 0 PID: 3365 Comm: fsstress Not tainted 4.10.0-nbor #134
[ 644.174012] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
[ 644.174012] Call Trace:
[ 644.174012] dump_stack+0x85/0xc9
[ 644.174012] print_usage_bug.part.37+0x284/0x293
[ 644.174012] ? print_shortest_lock_dependencies+0x1b0/0x1b0
[ 644.174012] mark_lock+0x27e/0x660
[ 644.174012] mark_held_locks+0x66/0x90
[ 644.174012] lockdep_trace_alloc+0x6f/0xd0
[ 644.174012] kmem_cache_alloc_node_trace+0x3a/0x2c0
[ 644.174012] ? vm_map_ram+0x2a1/0x510
[ 644.174012] vm_map_ram+0x2a1/0x510
[ 644.174012] ? vm_map_ram+0x46/0x510
[ 644.174012] _xfs_buf_map_pages+0x77/0x140
[ 644.174012] xfs_buf_get_map+0x185/0x2a0
[ 644.174012] xfs_attr_rmtval_set+0x233/0x430
[ 644.174012] xfs_attr_leaf_addname+0x2d2/0x500
[ 644.174012] xfs_attr_set+0x214/0x420
[ 644.174012] xfs_xattr_set+0x59/0xb0
[ 644.174012] __vfs_setxattr+0x76/0xa0
[ 644.174012] __vfs_setxattr_noperm+0x5e/0xf0
[ 644.174012] vfs_setxattr+0xae/0xb0
[ 644.174012] ? __might_fault+0x43/0xa0
[ 644.174012] setxattr+0x15e/0x1a0
[ 644.174012] ? __lock_is_held+0x53/0x90
[ 644.174012] ? rcu_read_lock_sched_held+0x93/0xa0
[ 644.174012] ? rcu_sync_lockdep_assert+0x2f/0x60
[ 644.174012] ? __sb_start_write+0x130/0x1d0
[ 644.174012] ? mnt_want_write+0x24/0x50
[ 644.174012] path_setxattr+0x8f/0xc0
[ 644.174012] SyS_lsetxattr+0x11/0x20
[ 644.174012] entry_SYSCALL_64_fastpath+0x23/0xc6
Let's fix this by making lockdep explicitly do the shaving of respective
GFP flags.
Fixes: 934f3072c17c ("mm: clear __GFP_FS when PF_MEMALLOC_NOIO is set")
Link: http://lkml.kernel.org/r/20170306131408.9828-2-mhocko@xxxxxxxxxx
Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx>
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Theodore Ts'o <tytso@xxxxxxx>
Cc: Chris Mason <clm@xxxxxx>
Cc: David Sterba <dsterba@xxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Brian Foster <bfoster@xxxxxxxxxx>
Cc: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/locking/lockdep.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff -puN kernel/locking/lockdep.c~lockdep-teach-lockdep-about-memalloc_noio_save kernel/locking/lockdep.c
--- a/kernel/locking/lockdep.c~lockdep-teach-lockdep-about-memalloc_noio_save
+++ a/kernel/locking/lockdep.c
@@ -30,6 +30,7 @@
#include <linux/sched.h>
#include <linux/sched/clock.h>
#include <linux/sched/task.h>
+#include <linux/sched/mm.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
@@ -2876,6 +2877,8 @@ static void __lockdep_trace_alloc(gfp_t
if (unlikely(!debug_locks))
return;
+ gfp_mask = memalloc_noio_flags(gfp_mask);
+
/* no reclaim without waiting on it */
if (!(gfp_mask & __GFP_DIRECT_RECLAIM))
return;
@@ -3947,7 +3950,7 @@ EXPORT_SYMBOL_GPL(lock_unpin_lock);
void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
{
- current->lockdep_reclaim_gfp = gfp_mask;
+ current->lockdep_reclaim_gfp = memalloc_noio_flags(gfp_mask);
}
void lockdep_clear_current_reclaim_state(void)
_
--
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