The patch titled
Subject: ocfs2: fix a potential 'ABBA' deadlock caused by 'l_lock' and 'dentry_attach_lock'
has been added to the -mm tree. Its filename is
ocfs2-fix-a-potential-abba-deadlock-caused-by-l_lock-and-dentry_attach_lock.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ocfs2-fix-a-potential-abba-deadlock-caused-by-l_lock-and-dentry_attach_lock.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/ocfs2-fix-a-potential-abba-deadlock-caused-by-l_lock-and-dentry_attach_lock.patch
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------------------------------------------------------
From: Jun Piao <piaojun@xxxxxxxxxx>
Subject: ocfs2: fix a potential 'ABBA' deadlock caused by 'l_lock' and 'dentry_attach_lock'
CPUA CPUB
ocfs2_dentry_convert_worker
get 'l_lock'
get 'dentry_attach_lock'
interruptted by dio_end_io:
dio_end_io
dio_bio_end_aio
dio_complete
dio->end_io
ocfs2_dio_end_io
ocfs2_rw_unlock
...
try to get 'l_lock'
but CPUA has got it.
We try to get 'dentry_attach_lock', but CPUB has taken
'dentry_attach_lock' and would not release it.
So we need use spin_lock_irqsave() for 'dentry_attach_lock' to prevent
interruption by softirq.
Link: http://lkml.kernel.org/r/5A2925FB.2060908@xxxxxxxxxx
Signed-off-by: Jun Piao <piaojun@xxxxxxxxxx>
Reviewed-by: Alex Chen <alex.chen@xxxxxxxxxx>
Cc: Mark Fasheh <mfasheh@xxxxxxxxxxx>
Cc: Joel Becker <jlbec@xxxxxxxxxxxx>
Cc: Junxiao Bi <junxiao.bi@xxxxxxxxxx>
Cc: Joseph Qi <jiangqi903@xxxxxxxxx>
Cc: Changwei Ge <ge.changwei@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/ocfs2/dcache.c | 14 ++++++++------
fs/ocfs2/dlmglue.c | 14 +++++++-------
fs/ocfs2/namei.c | 5 +++--
3 files changed, 18 insertions(+), 15 deletions(-)
diff -puN fs/ocfs2/dcache.c~ocfs2-fix-a-potential-abba-deadlock-caused-by-l_lock-and-dentry_attach_lock fs/ocfs2/dcache.c
--- a/fs/ocfs2/dcache.c~ocfs2-fix-a-potential-abba-deadlock-caused-by-l_lock-and-dentry_attach_lock
+++ a/fs/ocfs2/dcache.c
@@ -230,6 +230,7 @@ int ocfs2_dentry_attach_lock(struct dent
int ret;
struct dentry *alias;
struct ocfs2_dentry_lock *dl = dentry->d_fsdata;
+ unsigned long flags;
trace_ocfs2_dentry_attach_lock(dentry->d_name.len, dentry->d_name.name,
(unsigned long long)parent_blkno, dl);
@@ -309,10 +310,10 @@ int ocfs2_dentry_attach_lock(struct dent
ocfs2_dentry_lock_res_init(dl, parent_blkno, inode);
out_attach:
- spin_lock(&dentry_attach_lock);
+ spin_lock_irqsave(&dentry_attach_lock, flags);
dentry->d_fsdata = dl;
dl->dl_count++;
- spin_unlock(&dentry_attach_lock);
+ spin_unlock_irqrestore(&dentry_attach_lock, flags);
/*
* This actually gets us our PRMODE level lock. From now on,
@@ -333,9 +334,9 @@ out_attach:
if (ret < 0 && !alias) {
ocfs2_lock_res_free(&dl->dl_lockres);
BUG_ON(dl->dl_count != 1);
- spin_lock(&dentry_attach_lock);
+ spin_lock_irqsave(&dentry_attach_lock, flags);
dentry->d_fsdata = NULL;
- spin_unlock(&dentry_attach_lock);
+ spin_unlock_irqrestore(&dentry_attach_lock, flags);
kfree(dl);
iput(inode);
}
@@ -379,13 +380,14 @@ void ocfs2_dentry_lock_put(struct ocfs2_
struct ocfs2_dentry_lock *dl)
{
int unlock = 0;
+ unsigned long flags;
BUG_ON(dl->dl_count == 0);
- spin_lock(&dentry_attach_lock);
+ spin_lock_irqsave(&dentry_attach_lock, flags);
dl->dl_count--;
unlock = !dl->dl_count;
- spin_unlock(&dentry_attach_lock);
+ spin_unlock_irqrestore(&dentry_attach_lock, flags);
if (unlock)
ocfs2_drop_dentry_lock(osb, dl);
diff -puN fs/ocfs2/dlmglue.c~ocfs2-fix-a-potential-abba-deadlock-caused-by-l_lock-and-dentry_attach_lock fs/ocfs2/dlmglue.c
--- a/fs/ocfs2/dlmglue.c~ocfs2-fix-a-potential-abba-deadlock-caused-by-l_lock-and-dentry_attach_lock
+++ a/fs/ocfs2/dlmglue.c
@@ -3801,7 +3801,7 @@ static int ocfs2_dentry_convert_worker(s
struct ocfs2_dentry_lock *dl = ocfs2_lock_res_dl(lockres);
struct ocfs2_inode_info *oi = OCFS2_I(dl->dl_inode);
struct dentry *dentry;
- unsigned long flags;
+ unsigned long flags, d_flags;
int extra_ref = 0;
/*
@@ -3831,13 +3831,13 @@ static int ocfs2_dentry_convert_worker(s
* flag.
*/
spin_lock_irqsave(&lockres->l_lock, flags);
- spin_lock(&dentry_attach_lock);
+ spin_lock_irqsave(&dentry_attach_lock, d_flags);
if (!(lockres->l_flags & OCFS2_LOCK_FREEING)
&& dl->dl_count) {
dl->dl_count++;
extra_ref = 1;
}
- spin_unlock(&dentry_attach_lock);
+ spin_unlock_irqrestore(&dentry_attach_lock, d_flags);
spin_unlock_irqrestore(&lockres->l_lock, flags);
mlog(0, "extra_ref = %d\n", extra_ref);
@@ -3850,13 +3850,13 @@ static int ocfs2_dentry_convert_worker(s
if (!extra_ref)
return UNBLOCK_CONTINUE;
- spin_lock(&dentry_attach_lock);
+ spin_lock_irqsave(&dentry_attach_lock, d_flags);
while (1) {
dentry = ocfs2_find_local_alias(dl->dl_inode,
dl->dl_parent_blkno, 1);
if (!dentry)
break;
- spin_unlock(&dentry_attach_lock);
+ spin_unlock_irqrestore(&dentry_attach_lock, d_flags);
if (S_ISDIR(dl->dl_inode->i_mode))
shrink_dcache_parent(dentry);
@@ -3874,9 +3874,9 @@ static int ocfs2_dentry_convert_worker(s
d_delete(dentry);
dput(dentry);
- spin_lock(&dentry_attach_lock);
+ spin_lock_irqsave(&dentry_attach_lock, d_flags);
}
- spin_unlock(&dentry_attach_lock);
+ spin_unlock_irqrestore(&dentry_attach_lock, d_flags);
/*
* If we are the last holder of this dentry lock, there is no
diff -puN fs/ocfs2/namei.c~ocfs2-fix-a-potential-abba-deadlock-caused-by-l_lock-and-dentry_attach_lock fs/ocfs2/namei.c
--- a/fs/ocfs2/namei.c~ocfs2-fix-a-potential-abba-deadlock-caused-by-l_lock-and-dentry_attach_lock
+++ a/fs/ocfs2/namei.c
@@ -223,13 +223,14 @@ static void ocfs2_cleanup_add_entry_fail
struct dentry *dentry, struct inode *inode)
{
struct ocfs2_dentry_lock *dl = dentry->d_fsdata;
+ unsigned long flags;
ocfs2_simple_drop_lockres(osb, &dl->dl_lockres);
ocfs2_lock_res_free(&dl->dl_lockres);
BUG_ON(dl->dl_count != 1);
- spin_lock(&dentry_attach_lock);
+ spin_lock_irqsave(&dentry_attach_lock, flags);
dentry->d_fsdata = NULL;
- spin_unlock(&dentry_attach_lock);
+ spin_unlock_irqrestore(&dentry_attach_lock, flags);
kfree(dl);
iput(inode);
}
_
Patches currently in -mm which might be from piaojun@xxxxxxxxxx are
ocfs2-fix-a-potential-abba-deadlock-caused-by-l_lock-and-dentry_attach_lock.patch
ocfs2-dlm-wait-for-dlm-recovery-done-when-migrating-all-lockres.patch
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