* [rfc patch] fs,reiserfs: unlock superblock before callling reiserfs_quota_on_mount()
@ 2012-08-14 13:06 Mike Galbraith
2012-08-14 14:23 ` Steven Rostedt
2012-08-14 15:15 ` Frederic Weisbecker
0 siblings, 2 replies; 12+ messages in thread
From: Mike Galbraith @ 2012-08-14 13:06 UTC (permalink / raw)
To: linux-rt-users@vger.kernel.org; +Cc: Thomas Gleixner, Steven Rostedt
Greetings,
Using openSUSE's "partitioner" gizmo to set up a reiserfs partition with
quotas and whatnot enabled rewarded me with a deadlock.
In reiserfs/lock.c we see:
...
* Also this lock is often released before a call that could block because
* reiserfs performances were partially based on the release while schedule()
* property of the Bkl.
*/
void reiserfs_write_lock(struct super_block *s)
And in the problematic reiserfs_fill_super():
/*
* This function is called with the bkl, which also was the old
* locking used here.
* do_journal_begin() will soon check if we hold the lock (ie: was the
* bkl). This is likely because do_journal_begin() has several another
* callers because at this time, it doesn't seem to be necessary to
* protect against anything.
* Anyway, let's be conservative and lock for now.
*/
reiserfs_write_lock(s);
Given wishy-washy "be conservative for now", and "this lock is often
released before a call that could block", it seemed reasonable to trade
a little conservatism for a chance to return from the blocking
function.
If we hold the super block lock while calling reiserfs_quota_on_mount(), we can
deadlock - mount blocks kworker/3:2, and sleeps forever more.
crash> ps|grep UN
715 2 3 ffff880220734d30 UN 0.0 0 0 [kworker/3:2]
9369 9341 2 ffff88021ffb7560 UN 1.3 493404 123184 Xorg
9665 9664 3 ffff880225b92ab0 UN 0.0 47368 812 udisks-daemon
10635 10403 3 ffff880222f22c70 UN 0.0 14904 936 mount
crash> bt ffff880220734d30
PID: 715 TASK: ffff880220734d30 CPU: 3 COMMAND: "kworker/3:2"
#0 [ffff8802244c3c20] schedule at ffffffff8144584b
#1 [ffff8802244c3cc8] __rt_mutex_slowlock at ffffffff814472b3
#2 [ffff8802244c3d28] rt_mutex_slowlock at ffffffff814473f5
#3 [ffff8802244c3dc8] reiserfs_write_lock at ffffffffa05f28fd [reiserfs]
#4 [ffff8802244c3de8] flush_async_commits at ffffffffa05ec91d [reiserfs]
#5 [ffff8802244c3e08] process_one_work at ffffffff81073726
#6 [ffff8802244c3e68] worker_thread at ffffffff81073eba
#7 [ffff8802244c3ec8] kthread at ffffffff810782e0
#8 [ffff8802244c3f48] kernel_thread_helper at ffffffff81450064
crash> struct rt_mutex ffff880222e8f628
struct rt_mutex {
wait_lock = {
raw_lock = {
slock = 65537
}
},
wait_list = {
node_list = {
next = 0xffff8802244c3d48,
prev = 0xffff8802244c3d48
}
},
owner = 0xffff880222f22c71,
save_state = 0
}
crash> bt 0xffff880222f22c70
PID: 10635 TASK: ffff880222f22c70 CPU: 3 COMMAND: "mount"
#0 [ffff8802216a9868] schedule at ffffffff8144584b
#1 [ffff8802216a9910] schedule_timeout at ffffffff81446865
#2 [ffff8802216a99a0] wait_for_common at ffffffff81445f74
#3 [ffff8802216a9a30] flush_work at ffffffff810712d3
#4 [ffff8802216a9ab0] schedule_on_each_cpu at ffffffff81074463
#5 [ffff8802216a9ae0] invalidate_bdev at ffffffff81178aba
#6 [ffff8802216a9af0] vfs_load_quota_inode at ffffffff811a3632
#7 [ffff8802216a9b50] dquot_quota_on_mount at ffffffff811a375c
#8 [ffff8802216a9b80] finish_unfinished at ffffffffa05dd8b0 [reiserfs]
#9 [ffff8802216a9cc0] reiserfs_fill_super at ffffffffa05de825 [reiserfs]
#10 [ffff8802216a9d90] mount_bdev at ffffffff8114c93f
#11 [ffff8802216a9e00] mount_fs at ffffffff8114d035
#12 [ffff8802216a9e50] vfs_kern_mount at ffffffff81167d36
#13 [ffff8802216a9e90] do_kern_mount at ffffffff811692c3
#14 [ffff8802216a9ed0] do_mount at ffffffff8116adb5
#15 [ffff8802216a9f30] sys_mount at ffffffff8116b25a
#16 [ffff8802216a9f80] system_call_fastpath at ffffffff8144ef12
RIP: 00007f7b9303997a RSP: 00007ffff443c7a8 RFLAGS: 00010202
RAX: 00000000000000a5 RBX: ffffffff8144ef12 RCX: 00007f7b932e9ee0
RDX: 00007f7b93d9a400 RSI: 00007f7b93d9a3e0 RDI: 00007f7b93d9a3c0
RBP: 00007f7b93d9a2c0 R8: 00007f7b93d9a550 R9: 0000000000000001
R10: ffffffffc0ed040e R11: 0000000000000202 R12: 000000000000040e
R13: 0000000000000000 R14: 00000000c0ed040e R15: 00007ffff443ca20
ORIG_RAX: 00000000000000a5 CS: 0033 SS: 002b
Signed-off-by: Mike Galbraith <efault@gmx.de>
---
fs/reiserfs/super.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
--- a/fs/reiserfs/super.c
+++ b/fs/reiserfs/super.c
@@ -140,7 +140,13 @@ static int remove_save_link_only(struct
static int reiserfs_quota_on_mount(struct super_block *, int);
#endif
-/* look for uncompleted unlinks and truncates and complete them */
+/*
+ *look for uncompleted unlinks and truncates and complete them
+ *
+ * Called with super_block write locked. If quotas are enabled,
+ * we have to release/retake lest we call dquot_quota_on_mount(),
+ * proceed to schedule_on_each_cpu() and deadlock our own worker.
+ */
static int finish_unfinished(struct super_block *s)
{
INITIALIZE_PATH(path);
@@ -187,7 +193,9 @@ static int finish_unfinished(struct supe
quota_enabled[i] = 0;
continue;
}
+ reiserfs_write_unlock(s);
ret = reiserfs_quota_on_mount(s, i);
+ reiserfs_write_lock(s);
if (ret < 0)
reiserfs_warning(s, "reiserfs-2500",
"cannot turn on journaled "
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [rfc patch] fs,reiserfs: unlock superblock before callling reiserfs_quota_on_mount()
2012-08-14 13:06 [rfc patch] fs,reiserfs: unlock superblock before callling reiserfs_quota_on_mount() Mike Galbraith
@ 2012-08-14 14:23 ` Steven Rostedt
2012-08-14 14:39 ` Mike Galbraith
2012-08-14 15:15 ` Frederic Weisbecker
1 sibling, 1 reply; 12+ messages in thread
From: Steven Rostedt @ 2012-08-14 14:23 UTC (permalink / raw)
To: Mike Galbraith
Cc: linux-rt-users@vger.kernel.org, Thomas Gleixner,
Frederic Weisbecker, LKML
On Tue, 2012-08-14 at 15:06 +0200, Mike Galbraith wrote:
> Greetings,
>
> Using openSUSE's "partitioner" gizmo to set up a reiserfs partition with
> quotas and whatnot enabled rewarded me with a deadlock.
Is this just a -rt bug? Can't this deadlock also in mainline?
-- Steve
>
> In reiserfs/lock.c we see:
> ...
> * Also this lock is often released before a call that could block because
> * reiserfs performances were partially based on the release while schedule()
> * property of the Bkl.
> */
> void reiserfs_write_lock(struct super_block *s)
>
> And in the problematic reiserfs_fill_super():
> /*
> * This function is called with the bkl, which also was the old
> * locking used here.
> * do_journal_begin() will soon check if we hold the lock (ie: was the
> * bkl). This is likely because do_journal_begin() has several another
> * callers because at this time, it doesn't seem to be necessary to
> * protect against anything.
> * Anyway, let's be conservative and lock for now.
> */
> reiserfs_write_lock(s);
>
> Given wishy-washy "be conservative for now", and "this lock is often
> released before a call that could block", it seemed reasonable to trade
> a little conservatism for a chance to return from the blocking
> function.
>
> If we hold the super block lock while calling reiserfs_quota_on_mount(), we can
> deadlock - mount blocks kworker/3:2, and sleeps forever more.
>
> crash> ps|grep UN
> 715 2 3 ffff880220734d30 UN 0.0 0 0 [kworker/3:2]
> 9369 9341 2 ffff88021ffb7560 UN 1.3 493404 123184 Xorg
> 9665 9664 3 ffff880225b92ab0 UN 0.0 47368 812 udisks-daemon
> 10635 10403 3 ffff880222f22c70 UN 0.0 14904 936 mount
> crash> bt ffff880220734d30
> PID: 715 TASK: ffff880220734d30 CPU: 3 COMMAND: "kworker/3:2"
> #0 [ffff8802244c3c20] schedule at ffffffff8144584b
> #1 [ffff8802244c3cc8] __rt_mutex_slowlock at ffffffff814472b3
> #2 [ffff8802244c3d28] rt_mutex_slowlock at ffffffff814473f5
> #3 [ffff8802244c3dc8] reiserfs_write_lock at ffffffffa05f28fd [reiserfs]
> #4 [ffff8802244c3de8] flush_async_commits at ffffffffa05ec91d [reiserfs]
> #5 [ffff8802244c3e08] process_one_work at ffffffff81073726
> #6 [ffff8802244c3e68] worker_thread at ffffffff81073eba
> #7 [ffff8802244c3ec8] kthread at ffffffff810782e0
> #8 [ffff8802244c3f48] kernel_thread_helper at ffffffff81450064
>
> crash> struct rt_mutex ffff880222e8f628
> struct rt_mutex {
> wait_lock = {
> raw_lock = {
> slock = 65537
> }
> },
> wait_list = {
> node_list = {
> next = 0xffff8802244c3d48,
> prev = 0xffff8802244c3d48
> }
> },
> owner = 0xffff880222f22c71,
> save_state = 0
> }
> crash> bt 0xffff880222f22c70
> PID: 10635 TASK: ffff880222f22c70 CPU: 3 COMMAND: "mount"
> #0 [ffff8802216a9868] schedule at ffffffff8144584b
> #1 [ffff8802216a9910] schedule_timeout at ffffffff81446865
> #2 [ffff8802216a99a0] wait_for_common at ffffffff81445f74
> #3 [ffff8802216a9a30] flush_work at ffffffff810712d3
> #4 [ffff8802216a9ab0] schedule_on_each_cpu at ffffffff81074463
> #5 [ffff8802216a9ae0] invalidate_bdev at ffffffff81178aba
> #6 [ffff8802216a9af0] vfs_load_quota_inode at ffffffff811a3632
> #7 [ffff8802216a9b50] dquot_quota_on_mount at ffffffff811a375c
> #8 [ffff8802216a9b80] finish_unfinished at ffffffffa05dd8b0 [reiserfs]
> #9 [ffff8802216a9cc0] reiserfs_fill_super at ffffffffa05de825 [reiserfs]
> #10 [ffff8802216a9d90] mount_bdev at ffffffff8114c93f
> #11 [ffff8802216a9e00] mount_fs at ffffffff8114d035
> #12 [ffff8802216a9e50] vfs_kern_mount at ffffffff81167d36
> #13 [ffff8802216a9e90] do_kern_mount at ffffffff811692c3
> #14 [ffff8802216a9ed0] do_mount at ffffffff8116adb5
> #15 [ffff8802216a9f30] sys_mount at ffffffff8116b25a
> #16 [ffff8802216a9f80] system_call_fastpath at ffffffff8144ef12
> RIP: 00007f7b9303997a RSP: 00007ffff443c7a8 RFLAGS: 00010202
> RAX: 00000000000000a5 RBX: ffffffff8144ef12 RCX: 00007f7b932e9ee0
> RDX: 00007f7b93d9a400 RSI: 00007f7b93d9a3e0 RDI: 00007f7b93d9a3c0
> RBP: 00007f7b93d9a2c0 R8: 00007f7b93d9a550 R9: 0000000000000001
> R10: ffffffffc0ed040e R11: 0000000000000202 R12: 000000000000040e
> R13: 0000000000000000 R14: 00000000c0ed040e R15: 00007ffff443ca20
> ORIG_RAX: 00000000000000a5 CS: 0033 SS: 002b
>
> Signed-off-by: Mike Galbraith <efault@gmx.de>
> ---
> fs/reiserfs/super.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> --- a/fs/reiserfs/super.c
> +++ b/fs/reiserfs/super.c
> @@ -140,7 +140,13 @@ static int remove_save_link_only(struct
> static int reiserfs_quota_on_mount(struct super_block *, int);
> #endif
>
> -/* look for uncompleted unlinks and truncates and complete them */
> +/*
> + *look for uncompleted unlinks and truncates and complete them
> + *
> + * Called with super_block write locked. If quotas are enabled,
> + * we have to release/retake lest we call dquot_quota_on_mount(),
> + * proceed to schedule_on_each_cpu() and deadlock our own worker.
> + */
> static int finish_unfinished(struct super_block *s)
> {
> INITIALIZE_PATH(path);
> @@ -187,7 +193,9 @@ static int finish_unfinished(struct supe
> quota_enabled[i] = 0;
> continue;
> }
> + reiserfs_write_unlock(s);
> ret = reiserfs_quota_on_mount(s, i);
> + reiserfs_write_lock(s);
> if (ret < 0)
> reiserfs_warning(s, "reiserfs-2500",
> "cannot turn on journaled "
>
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [rfc patch] fs,reiserfs: unlock superblock before callling reiserfs_quota_on_mount()
2012-08-14 14:23 ` Steven Rostedt
@ 2012-08-14 14:39 ` Mike Galbraith
2012-08-14 14:56 ` Mike Galbraith
0 siblings, 1 reply; 12+ messages in thread
From: Mike Galbraith @ 2012-08-14 14:39 UTC (permalink / raw)
To: Steven Rostedt
Cc: linux-rt-users@vger.kernel.org, Thomas Gleixner,
Frederic Weisbecker, LKML
On Tue, 2012-08-14 at 10:23 -0400, Steven Rostedt wrote:
> On Tue, 2012-08-14 at 15:06 +0200, Mike Galbraith wrote:
> > Greetings,
> >
> > Using openSUSE's "partitioner" gizmo to set up a reiserfs partition with
> > quotas and whatnot enabled rewarded me with a deadlock.
>
> Is this just a -rt bug? Can't this deadlock also in mainline?
It didn't with a NOPREEMPT kernel the one time I tried it, which seemed
mighty odd when I stared at the rt deadlock. I'll give it another go, I
likely just munged q/d NOPREEMPT test.
-Mike
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [rfc patch] fs,reiserfs: unlock superblock before callling reiserfs_quota_on_mount()
2012-08-14 14:39 ` Mike Galbraith
@ 2012-08-14 14:56 ` Mike Galbraith
2012-08-14 15:18 ` Thomas Gleixner
0 siblings, 1 reply; 12+ messages in thread
From: Mike Galbraith @ 2012-08-14 14:56 UTC (permalink / raw)
To: Steven Rostedt
Cc: linux-rt-users@vger.kernel.org, Thomas Gleixner,
Frederic Weisbecker, LKML
On Tue, 2012-08-14 at 16:39 +0200, Mike Galbraith wrote:
> On Tue, 2012-08-14 at 10:23 -0400, Steven Rostedt wrote:
> > On Tue, 2012-08-14 at 15:06 +0200, Mike Galbraith wrote:
> > > Greetings,
> > >
> > > Using openSUSE's "partitioner" gizmo to set up a reiserfs partition with
> > > quotas and whatnot enabled rewarded me with a deadlock.
> >
> > Is this just a -rt bug? Can't this deadlock also in mainline?
>
> It didn't with a NOPREEMPT kernel the one time I tried it, which seemed
> mighty odd when I stared at the rt deadlock. I'll give it another go, I
> likely just munged q/d NOPREEMPT test.
Nope, no screw-up. Maybe it can deadlock, but it refused to do so.
-Mike
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [rfc patch] fs,reiserfs: unlock superblock before callling reiserfs_quota_on_mount()
2012-08-14 13:06 [rfc patch] fs,reiserfs: unlock superblock before callling reiserfs_quota_on_mount() Mike Galbraith
2012-08-14 14:23 ` Steven Rostedt
@ 2012-08-14 15:15 ` Frederic Weisbecker
2012-08-16 12:44 ` [patch] " Mike Galbraith
1 sibling, 1 reply; 12+ messages in thread
From: Frederic Weisbecker @ 2012-08-14 15:15 UTC (permalink / raw)
To: Mike Galbraith
Cc: linux-rt-users@vger.kernel.org, Thomas Gleixner, Steven Rostedt
On Tue, Aug 14, 2012 at 03:06:23PM +0200, Mike Galbraith wrote:
> Greetings,
>
> Using openSUSE's "partitioner" gizmo to set up a reiserfs partition with
> quotas and whatnot enabled rewarded me with a deadlock.
>
> In reiserfs/lock.c we see:
> ...
> * Also this lock is often released before a call that could block because
> * reiserfs performances were partially based on the release while schedule()
> * property of the Bkl.
> */
> void reiserfs_write_lock(struct super_block *s)
>
> And in the problematic reiserfs_fill_super():
> /*
> * This function is called with the bkl, which also was the old
> * locking used here.
> * do_journal_begin() will soon check if we hold the lock (ie: was the
> * bkl). This is likely because do_journal_begin() has several another
> * callers because at this time, it doesn't seem to be necessary to
> * protect against anything.
> * Anyway, let's be conservative and lock for now.
> */
> reiserfs_write_lock(s);
>
> Given wishy-washy "be conservative for now", and "this lock is often
> released before a call that could block", it seemed reasonable to trade
> a little conservatism for a chance to return from the blocking
> function.
>
> If we hold the super block lock while calling reiserfs_quota_on_mount(), we can
> deadlock - mount blocks kworker/3:2, and sleeps forever more.
>
> crash> ps|grep UN
> 715 2 3 ffff880220734d30 UN 0.0 0 0 [kworker/3:2]
> 9369 9341 2 ffff88021ffb7560 UN 1.3 493404 123184 Xorg
> 9665 9664 3 ffff880225b92ab0 UN 0.0 47368 812 udisks-daemon
> 10635 10403 3 ffff880222f22c70 UN 0.0 14904 936 mount
> crash> bt ffff880220734d30
> PID: 715 TASK: ffff880220734d30 CPU: 3 COMMAND: "kworker/3:2"
> #0 [ffff8802244c3c20] schedule at ffffffff8144584b
> #1 [ffff8802244c3cc8] __rt_mutex_slowlock at ffffffff814472b3
> #2 [ffff8802244c3d28] rt_mutex_slowlock at ffffffff814473f5
> #3 [ffff8802244c3dc8] reiserfs_write_lock at ffffffffa05f28fd [reiserfs]
> #4 [ffff8802244c3de8] flush_async_commits at ffffffffa05ec91d [reiserfs]
> #5 [ffff8802244c3e08] process_one_work at ffffffff81073726
> #6 [ffff8802244c3e68] worker_thread at ffffffff81073eba
> #7 [ffff8802244c3ec8] kthread at ffffffff810782e0
> #8 [ffff8802244c3f48] kernel_thread_helper at ffffffff81450064
>
> crash> struct rt_mutex ffff880222e8f628
> struct rt_mutex {
> wait_lock = {
> raw_lock = {
> slock = 65537
> }
> },
> wait_list = {
> node_list = {
> next = 0xffff8802244c3d48,
> prev = 0xffff8802244c3d48
> }
> },
> owner = 0xffff880222f22c71,
> save_state = 0
> }
> crash> bt 0xffff880222f22c70
> PID: 10635 TASK: ffff880222f22c70 CPU: 3 COMMAND: "mount"
> #0 [ffff8802216a9868] schedule at ffffffff8144584b
> #1 [ffff8802216a9910] schedule_timeout at ffffffff81446865
> #2 [ffff8802216a99a0] wait_for_common at ffffffff81445f74
> #3 [ffff8802216a9a30] flush_work at ffffffff810712d3
> #4 [ffff8802216a9ab0] schedule_on_each_cpu at ffffffff81074463
> #5 [ffff8802216a9ae0] invalidate_bdev at ffffffff81178aba
> #6 [ffff8802216a9af0] vfs_load_quota_inode at ffffffff811a3632
> #7 [ffff8802216a9b50] dquot_quota_on_mount at ffffffff811a375c
> #8 [ffff8802216a9b80] finish_unfinished at ffffffffa05dd8b0 [reiserfs]
> #9 [ffff8802216a9cc0] reiserfs_fill_super at ffffffffa05de825 [reiserfs]
> #10 [ffff8802216a9d90] mount_bdev at ffffffff8114c93f
> #11 [ffff8802216a9e00] mount_fs at ffffffff8114d035
> #12 [ffff8802216a9e50] vfs_kern_mount at ffffffff81167d36
> #13 [ffff8802216a9e90] do_kern_mount at ffffffff811692c3
> #14 [ffff8802216a9ed0] do_mount at ffffffff8116adb5
> #15 [ffff8802216a9f30] sys_mount at ffffffff8116b25a
> #16 [ffff8802216a9f80] system_call_fastpath at ffffffff8144ef12
> RIP: 00007f7b9303997a RSP: 00007ffff443c7a8 RFLAGS: 00010202
> RAX: 00000000000000a5 RBX: ffffffff8144ef12 RCX: 00007f7b932e9ee0
> RDX: 00007f7b93d9a400 RSI: 00007f7b93d9a3e0 RDI: 00007f7b93d9a3c0
> RBP: 00007f7b93d9a2c0 R8: 00007f7b93d9a550 R9: 0000000000000001
> R10: ffffffffc0ed040e R11: 0000000000000202 R12: 000000000000040e
> R13: 0000000000000000 R14: 00000000c0ed040e R15: 00007ffff443ca20
> ORIG_RAX: 00000000000000a5 CS: 0033 SS: 002b
>
> Signed-off-by: Mike Galbraith <efault@gmx.de>
Looks ok. Thanks.
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [rfc patch] fs,reiserfs: unlock superblock before callling reiserfs_quota_on_mount()
2012-08-14 14:56 ` Mike Galbraith
@ 2012-08-14 15:18 ` Thomas Gleixner
2012-08-14 17:26 ` Mike Galbraith
0 siblings, 1 reply; 12+ messages in thread
From: Thomas Gleixner @ 2012-08-14 15:18 UTC (permalink / raw)
To: Mike Galbraith
Cc: Steven Rostedt, linux-rt-users@vger.kernel.org,
Frederic Weisbecker, LKML
On Tue, 14 Aug 2012, Mike Galbraith wrote:
> On Tue, 2012-08-14 at 16:39 +0200, Mike Galbraith wrote:
> > On Tue, 2012-08-14 at 10:23 -0400, Steven Rostedt wrote:
> > > On Tue, 2012-08-14 at 15:06 +0200, Mike Galbraith wrote:
> > > > Greetings,
> > > >
> > > > Using openSUSE's "partitioner" gizmo to set up a reiserfs partition with
> > > > quotas and whatnot enabled rewarded me with a deadlock.
> > >
> > > Is this just a -rt bug? Can't this deadlock also in mainline?
> >
> > It didn't with a NOPREEMPT kernel the one time I tried it, which seemed
> > mighty odd when I stared at the rt deadlock. I'll give it another go, I
> > likely just munged q/d NOPREEMPT test.
>
> Nope, no screw-up. Maybe it can deadlock, but it refused to do so.
Lockdep should tell you if it could ...
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [rfc patch] fs,reiserfs: unlock superblock before callling reiserfs_quota_on_mount()
2012-08-14 15:18 ` Thomas Gleixner
@ 2012-08-14 17:26 ` Mike Galbraith
2012-08-14 17:44 ` Steven Rostedt
0 siblings, 1 reply; 12+ messages in thread
From: Mike Galbraith @ 2012-08-14 17:26 UTC (permalink / raw)
To: Thomas Gleixner
Cc: Steven Rostedt, linux-rt-users@vger.kernel.org,
Frederic Weisbecker, LKML
On Tue, 2012-08-14 at 17:18 +0200, Thomas Gleixner wrote:
> On Tue, 14 Aug 2012, Mike Galbraith wrote:
>
> > On Tue, 2012-08-14 at 16:39 +0200, Mike Galbraith wrote:
> > > On Tue, 2012-08-14 at 10:23 -0400, Steven Rostedt wrote:
> > > > On Tue, 2012-08-14 at 15:06 +0200, Mike Galbraith wrote:
> > > > > Greetings,
> > > > >
> > > > > Using openSUSE's "partitioner" gizmo to set up a reiserfs partition with
> > > > > quotas and whatnot enabled rewarded me with a deadlock.
> > > >
> > > > Is this just a -rt bug? Can't this deadlock also in mainline?
> > >
> > > It didn't with a NOPREEMPT kernel the one time I tried it, which seemed
> > > mighty odd when I stared at the rt deadlock. I'll give it another go, I
> > > likely just munged q/d NOPREEMPT test.
> >
> > Nope, no screw-up. Maybe it can deadlock, but it refused to do so.
>
> Lockdep should tell you if it could ...
I'll give that a shot. I would expect the thing to gripe.. but then I
expected the damn thing to deadlock properly with NOPREEMPT too, so.. :)
-Mike
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [rfc patch] fs,reiserfs: unlock superblock before callling reiserfs_quota_on_mount()
2012-08-14 17:26 ` Mike Galbraith
@ 2012-08-14 17:44 ` Steven Rostedt
2012-08-14 18:09 ` Mike Galbraith
0 siblings, 1 reply; 12+ messages in thread
From: Steven Rostedt @ 2012-08-14 17:44 UTC (permalink / raw)
To: Mike Galbraith
Cc: Thomas Gleixner, linux-rt-users@vger.kernel.org,
Frederic Weisbecker, LKML
On Tue, 2012-08-14 at 19:26 +0200, Mike Galbraith wrote:
> On Tue, 2012-08-14 at 17:18 +0200, Thomas Gleixner wrote:
> > On Tue, 14 Aug 2012, Mike Galbraith wrote:
> >
> > > On Tue, 2012-08-14 at 16:39 +0200, Mike Galbraith wrote:
> > > > On Tue, 2012-08-14 at 10:23 -0400, Steven Rostedt wrote:
> > > > > On Tue, 2012-08-14 at 15:06 +0200, Mike Galbraith wrote:
> > > > > > Greetings,
> > > > > >
> > > > > > Using openSUSE's "partitioner" gizmo to set up a reiserfs partition with
> > > > > > quotas and whatnot enabled rewarded me with a deadlock.
> > > > >
> > > > > Is this just a -rt bug? Can't this deadlock also in mainline?
> > > >
> > > > It didn't with a NOPREEMPT kernel the one time I tried it, which seemed
> > > > mighty odd when I stared at the rt deadlock. I'll give it another go, I
> > > > likely just munged q/d NOPREEMPT test.
> > >
> > > Nope, no screw-up. Maybe it can deadlock, but it refused to do so.
> >
> > Lockdep should tell you if it could ...
>
> I'll give that a shot. I would expect the thing to gripe.. but then I
> expected the damn thing to deadlock properly with NOPREEMPT too, so.. :)
>
But would it?
We have kworker blocked on the mutex where the owner did a flush_work(),
and waiting for kworker to finish because of a wait_for_completion(). I
don't see annotation here that will help lockdep catch such a thing.
-- Steve
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [rfc patch] fs,reiserfs: unlock superblock before callling reiserfs_quota_on_mount()
2012-08-14 17:44 ` Steven Rostedt
@ 2012-08-14 18:09 ` Mike Galbraith
0 siblings, 0 replies; 12+ messages in thread
From: Mike Galbraith @ 2012-08-14 18:09 UTC (permalink / raw)
To: Steven Rostedt
Cc: Thomas Gleixner, linux-rt-users@vger.kernel.org,
Frederic Weisbecker, LKML
On Tue, 2012-08-14 at 13:44 -0400, Steven Rostedt wrote:
> On Tue, 2012-08-14 at 19:26 +0200, Mike Galbraith wrote:
> > On Tue, 2012-08-14 at 17:18 +0200, Thomas Gleixner wrote:
> > > On Tue, 14 Aug 2012, Mike Galbraith wrote:
> > >
> > > > On Tue, 2012-08-14 at 16:39 +0200, Mike Galbraith wrote:
> > > > > On Tue, 2012-08-14 at 10:23 -0400, Steven Rostedt wrote:
> > > > > > On Tue, 2012-08-14 at 15:06 +0200, Mike Galbraith wrote:
> > > > > > > Greetings,
> > > > > > >
> > > > > > > Using openSUSE's "partitioner" gizmo to set up a reiserfs partition with
> > > > > > > quotas and whatnot enabled rewarded me with a deadlock.
> > > > > >
> > > > > > Is this just a -rt bug? Can't this deadlock also in mainline?
> > > > >
> > > > > It didn't with a NOPREEMPT kernel the one time I tried it, which seemed
> > > > > mighty odd when I stared at the rt deadlock. I'll give it another go, I
> > > > > likely just munged q/d NOPREEMPT test.
> > > >
> > > > Nope, no screw-up. Maybe it can deadlock, but it refused to do so.
> > >
> > > Lockdep should tell you if it could ...
> >
> > I'll give that a shot. I would expect the thing to gripe.. but then I
> > expected the damn thing to deadlock properly with NOPREEMPT too, so.. :)
> >
>
> But would it?
>
> We have kworker blocked on the mutex where the owner did a flush_work(),
> and waiting for kworker to finish because of a wait_for_completion(). I
> don't see annotation here that will help lockdep catch such a thing.
Hm.. <zzzt>. Ok, you saved me a long kernel build, but cost me a fuse.
-Mike
^ permalink raw reply [flat|nested] 12+ messages in thread
* [patch] fs,reiserfs: unlock superblock before callling reiserfs_quota_on_mount()
2012-08-14 15:15 ` Frederic Weisbecker
@ 2012-08-16 12:44 ` Mike Galbraith
2012-08-16 13:05 ` Frederic Weisbecker
0 siblings, 1 reply; 12+ messages in thread
From: Mike Galbraith @ 2012-08-16 12:44 UTC (permalink / raw)
To: Frederic Weisbecker; +Cc: Thomas Gleixner, Steven Rostedt, reiserfs-devel, RT
On Tue, 2012-08-14 at 17:15 +0200, Frederic Weisbecker wrote:
> Looks ok. Thanks.
>
> Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Thanks. Slightly reworded patchlet below.
If we hold the superblock lock while calling reiserfs_quota_on_mount(), we can
deadlock our own worker - mount blocks kworker/3:2, sleeps forever more.
crash> ps|grep UN
715 2 3 ffff880220734d30 UN 0.0 0 0 [kworker/3:2]
9369 9341 2 ffff88021ffb7560 UN 1.3 493404 123184 Xorg
9665 9664 3 ffff880225b92ab0 UN 0.0 47368 812 udisks-daemon
10635 10403 3 ffff880222f22c70 UN 0.0 14904 936 mount
crash> bt ffff880220734d30
PID: 715 TASK: ffff880220734d30 CPU: 3 COMMAND: "kworker/3:2"
#0 [ffff8802244c3c20] schedule at ffffffff8144584b
#1 [ffff8802244c3cc8] __rt_mutex_slowlock at ffffffff814472b3
#2 [ffff8802244c3d28] rt_mutex_slowlock at ffffffff814473f5
#3 [ffff8802244c3dc8] reiserfs_write_lock at ffffffffa05f28fd [reiserfs]
#4 [ffff8802244c3de8] flush_async_commits at ffffffffa05ec91d [reiserfs]
#5 [ffff8802244c3e08] process_one_work at ffffffff81073726
#6 [ffff8802244c3e68] worker_thread at ffffffff81073eba
#7 [ffff8802244c3ec8] kthread at ffffffff810782e0
#8 [ffff8802244c3f48] kernel_thread_helper at ffffffff81450064
crash> rd ffff8802244c3cc8 10
ffff8802244c3cc8: ffffffff814472b3 ffff880222f23250 .rD.....P2."....
ffff8802244c3cd8: 0000000000000000 0000000000000286 ................
ffff8802244c3ce8: ffff8802244c3d30 ffff880220734d80 0=L$.....Ms ....
ffff8802244c3cf8: ffff880222e8f628 0000000000000000 (.."............
ffff8802244c3d08: 0000000000000000 0000000000000002 ................
crash> struct rt_mutex ffff880222e8f628
struct rt_mutex {
wait_lock = {
raw_lock = {
slock = 65537
}
},
wait_list = {
node_list = {
next = 0xffff8802244c3d48,
prev = 0xffff8802244c3d48
}
},
owner = 0xffff880222f22c71,
save_state = 0
}
crash> bt 0xffff880222f22c70
PID: 10635 TASK: ffff880222f22c70 CPU: 3 COMMAND: "mount"
#0 [ffff8802216a9868] schedule at ffffffff8144584b
#1 [ffff8802216a9910] schedule_timeout at ffffffff81446865
#2 [ffff8802216a99a0] wait_for_common at ffffffff81445f74
#3 [ffff8802216a9a30] flush_work at ffffffff810712d3
#4 [ffff8802216a9ab0] schedule_on_each_cpu at ffffffff81074463
#5 [ffff8802216a9ae0] invalidate_bdev at ffffffff81178aba
#6 [ffff8802216a9af0] vfs_load_quota_inode at ffffffff811a3632
#7 [ffff8802216a9b50] dquot_quota_on_mount at ffffffff811a375c
#8 [ffff8802216a9b80] finish_unfinished at ffffffffa05dd8b0 [reiserfs]
#9 [ffff8802216a9cc0] reiserfs_fill_super at ffffffffa05de825 [reiserfs]
#10 [ffff8802216a9d90] mount_bdev at ffffffff8114c93f
#11 [ffff8802216a9e00] mount_fs at ffffffff8114d035
#12 [ffff8802216a9e50] vfs_kern_mount at ffffffff81167d36
#13 [ffff8802216a9e90] do_kern_mount at ffffffff811692c3
#14 [ffff8802216a9ed0] do_mount at ffffffff8116adb5
#15 [ffff8802216a9f30] sys_mount at ffffffff8116b25a
#16 [ffff8802216a9f80] system_call_fastpath at ffffffff8144ef12
RIP: 00007f7b9303997a RSP: 00007ffff443c7a8 RFLAGS: 00010202
RAX: 00000000000000a5 RBX: ffffffff8144ef12 RCX: 00007f7b932e9ee0
RDX: 00007f7b93d9a400 RSI: 00007f7b93d9a3e0 RDI: 00007f7b93d9a3c0
RBP: 00007f7b93d9a2c0 R8: 00007f7b93d9a550 R9: 0000000000000001
R10: ffffffffc0ed040e R11: 0000000000000202 R12: 000000000000040e
R13: 0000000000000000 R14: 00000000c0ed040e R15: 00007ffff443ca20
ORIG_RAX: 00000000000000a5 CS: 0033 SS: 002b
Signed-off-by: Mike Galbraith <efault@gmx.de>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: stable <stable@vger.kernel.org>
---
fs/reiserfs/super.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
--- a/fs/reiserfs/super.c
+++ b/fs/reiserfs/super.c
@@ -184,7 +184,13 @@ static int remove_save_link_only(struct
static int reiserfs_quota_on_mount(struct super_block *, int);
#endif
-/* look for uncompleted unlinks and truncates and complete them */
+/*
+ *look for uncompleted unlinks and truncates and complete them
+ *
+ * Called with super_block write locked. If quotas are enabled,
+ * we have to release/retake lest we call dquot_quota_on_mount(),
+ * proceed to schedule_on_each_cpu() and deadlock our own worker.
+ */
static int finish_unfinished(struct super_block *s)
{
INITIALIZE_PATH(path);
@@ -231,7 +237,9 @@ static int finish_unfinished(struct supe
quota_enabled[i] = 0;
continue;
}
+ reiserfs_write_unlock(s);
ret = reiserfs_quota_on_mount(s, i);
+ reiserfs_write_lock(s);
if (ret < 0)
reiserfs_warning(s, "reiserfs-2500",
"cannot turn on journaled "
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [patch] fs,reiserfs: unlock superblock before callling reiserfs_quota_on_mount()
2012-08-16 12:44 ` [patch] " Mike Galbraith
@ 2012-08-16 13:05 ` Frederic Weisbecker
2012-08-16 13:49 ` Mike Galbraith
0 siblings, 1 reply; 12+ messages in thread
From: Frederic Weisbecker @ 2012-08-16 13:05 UTC (permalink / raw)
To: Mike Galbraith; +Cc: Thomas Gleixner, Steven Rostedt, reiserfs-devel, RT
On Thu, Aug 16, 2012 at 02:44:34PM +0200, Mike Galbraith wrote:
> On Tue, 2012-08-14 at 17:15 +0200, Frederic Weisbecker wrote:
>
> > Looks ok. Thanks.
> >
> > Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
>
> Thanks. Slightly reworded patchlet below.
>
>
> If we hold the superblock lock while calling reiserfs_quota_on_mount(), we can
> deadlock our own worker - mount blocks kworker/3:2, sleeps forever more.
>
> crash> ps|grep UN
> 715 2 3 ffff880220734d30 UN 0.0 0 0 [kworker/3:2]
> 9369 9341 2 ffff88021ffb7560 UN 1.3 493404 123184 Xorg
> 9665 9664 3 ffff880225b92ab0 UN 0.0 47368 812 udisks-daemon
> 10635 10403 3 ffff880222f22c70 UN 0.0 14904 936 mount
> crash> bt ffff880220734d30
> PID: 715 TASK: ffff880220734d30 CPU: 3 COMMAND: "kworker/3:2"
> #0 [ffff8802244c3c20] schedule at ffffffff8144584b
> #1 [ffff8802244c3cc8] __rt_mutex_slowlock at ffffffff814472b3
> #2 [ffff8802244c3d28] rt_mutex_slowlock at ffffffff814473f5
> #3 [ffff8802244c3dc8] reiserfs_write_lock at ffffffffa05f28fd [reiserfs]
> #4 [ffff8802244c3de8] flush_async_commits at ffffffffa05ec91d [reiserfs]
> #5 [ffff8802244c3e08] process_one_work at ffffffff81073726
> #6 [ffff8802244c3e68] worker_thread at ffffffff81073eba
> #7 [ffff8802244c3ec8] kthread at ffffffff810782e0
> #8 [ffff8802244c3f48] kernel_thread_helper at ffffffff81450064
> crash> rd ffff8802244c3cc8 10
> ffff8802244c3cc8: ffffffff814472b3 ffff880222f23250 .rD.....P2."....
> ffff8802244c3cd8: 0000000000000000 0000000000000286 ................
> ffff8802244c3ce8: ffff8802244c3d30 ffff880220734d80 0=L$.....Ms ....
> ffff8802244c3cf8: ffff880222e8f628 0000000000000000 (.."............
> ffff8802244c3d08: 0000000000000000 0000000000000002 ................
> crash> struct rt_mutex ffff880222e8f628
> struct rt_mutex {
> wait_lock = {
> raw_lock = {
> slock = 65537
> }
> },
> wait_list = {
> node_list = {
> next = 0xffff8802244c3d48,
> prev = 0xffff8802244c3d48
> }
> },
> owner = 0xffff880222f22c71,
> save_state = 0
> }
> crash> bt 0xffff880222f22c70
> PID: 10635 TASK: ffff880222f22c70 CPU: 3 COMMAND: "mount"
> #0 [ffff8802216a9868] schedule at ffffffff8144584b
> #1 [ffff8802216a9910] schedule_timeout at ffffffff81446865
> #2 [ffff8802216a99a0] wait_for_common at ffffffff81445f74
> #3 [ffff8802216a9a30] flush_work at ffffffff810712d3
> #4 [ffff8802216a9ab0] schedule_on_each_cpu at ffffffff81074463
> #5 [ffff8802216a9ae0] invalidate_bdev at ffffffff81178aba
> #6 [ffff8802216a9af0] vfs_load_quota_inode at ffffffff811a3632
> #7 [ffff8802216a9b50] dquot_quota_on_mount at ffffffff811a375c
> #8 [ffff8802216a9b80] finish_unfinished at ffffffffa05dd8b0 [reiserfs]
> #9 [ffff8802216a9cc0] reiserfs_fill_super at ffffffffa05de825 [reiserfs]
> #10 [ffff8802216a9d90] mount_bdev at ffffffff8114c93f
> #11 [ffff8802216a9e00] mount_fs at ffffffff8114d035
> #12 [ffff8802216a9e50] vfs_kern_mount at ffffffff81167d36
> #13 [ffff8802216a9e90] do_kern_mount at ffffffff811692c3
> #14 [ffff8802216a9ed0] do_mount at ffffffff8116adb5
> #15 [ffff8802216a9f30] sys_mount at ffffffff8116b25a
> #16 [ffff8802216a9f80] system_call_fastpath at ffffffff8144ef12
> RIP: 00007f7b9303997a RSP: 00007ffff443c7a8 RFLAGS: 00010202
> RAX: 00000000000000a5 RBX: ffffffff8144ef12 RCX: 00007f7b932e9ee0
> RDX: 00007f7b93d9a400 RSI: 00007f7b93d9a3e0 RDI: 00007f7b93d9a3c0
> RBP: 00007f7b93d9a2c0 R8: 00007f7b93d9a550 R9: 0000000000000001
> R10: ffffffffc0ed040e R11: 0000000000000202 R12: 000000000000040e
> R13: 0000000000000000 R14: 00000000c0ed040e R15: 00007ffff443ca20
> ORIG_RAX: 00000000000000a5 CS: 0033 SS: 002b
>
> Signed-off-by: Mike Galbraith <efault@gmx.de>
> Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: stable <stable@vger.kernel.org>
> ---
> fs/reiserfs/super.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> --- a/fs/reiserfs/super.c
> +++ b/fs/reiserfs/super.c
> @@ -184,7 +184,13 @@ static int remove_save_link_only(struct
> static int reiserfs_quota_on_mount(struct super_block *, int);
> #endif
>
> -/* look for uncompleted unlinks and truncates and complete them */
> +/*
> + *look for uncompleted unlinks and truncates and complete them
> + *
> + * Called with super_block write locked. If quotas are enabled,
> + * we have to release/retake lest we call dquot_quota_on_mount(),
> + * proceed to schedule_on_each_cpu() and deadlock our own worker.
Could you please mention in the comment that the real issue is that we wait for
the per cpu worklets to complete flush_async_commits() that in turn wait for
the superblock write lock? schedule_on_each_cpu() in itself is not the problem.
Otherwise it might sound confusing.
Thanks.
> + */
> static int finish_unfinished(struct super_block *s)
> {
> INITIALIZE_PATH(path);
> @@ -231,7 +237,9 @@ static int finish_unfinished(struct supe
> quota_enabled[i] = 0;
> continue;
> }
> + reiserfs_write_unlock(s);
> ret = reiserfs_quota_on_mount(s, i);
> + reiserfs_write_lock(s);
> if (ret < 0)
> reiserfs_warning(s, "reiserfs-2500",
> "cannot turn on journaled "
>
>
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [patch] fs,reiserfs: unlock superblock before callling reiserfs_quota_on_mount()
2012-08-16 13:05 ` Frederic Weisbecker
@ 2012-08-16 13:49 ` Mike Galbraith
0 siblings, 0 replies; 12+ messages in thread
From: Mike Galbraith @ 2012-08-16 13:49 UTC (permalink / raw)
To: Frederic Weisbecker; +Cc: Thomas Gleixner, Steven Rostedt, reiserfs-devel, RT
On Thu, 2012-08-16 at 15:05 +0200, Frederic Weisbecker wrote:
> On Thu, Aug 16, 2012 at 02:44:34PM +0200, Mike Galbraith wrote:
> > --- a/fs/reiserfs/super.c
> > +++ b/fs/reiserfs/super.c
> > @@ -184,7 +184,13 @@ static int remove_save_link_only(struct
> > static int reiserfs_quota_on_mount(struct super_block *, int);
> > #endif
> >
> > -/* look for uncompleted unlinks and truncates and complete them */
> > +/*
> > + *look for uncompleted unlinks and truncates and complete them
> > + *
> > + * Called with super_block write locked. If quotas are enabled,
> > + * we have to release/retake lest we call dquot_quota_on_mount(),
> > + * proceed to schedule_on_each_cpu() and deadlock our own worker.
>
> Could you please mention in the comment that the real issue is that we wait for
> the per cpu worklets to complete flush_async_commits() that in turn wait for
> the superblock write lock? schedule_on_each_cpu() in itself is not the problem.
> Otherwise it might sound confusing.
>
> Thanks.
Done (stealing your text).
If we hold the superblock lock while calling reiserfs_quota_on_mount(), we can
deadlock our own worker - mount blocks kworker/3:2, sleeps forever more.
crash> ps|grep UN
715 2 3 ffff880220734d30 UN 0.0 0 0 [kworker/3:2]
9369 9341 2 ffff88021ffb7560 UN 1.3 493404 123184 Xorg
9665 9664 3 ffff880225b92ab0 UN 0.0 47368 812 udisks-daemon
10635 10403 3 ffff880222f22c70 UN 0.0 14904 936 mount
crash> bt ffff880220734d30
PID: 715 TASK: ffff880220734d30 CPU: 3 COMMAND: "kworker/3:2"
#0 [ffff8802244c3c20] schedule at ffffffff8144584b
#1 [ffff8802244c3cc8] __rt_mutex_slowlock at ffffffff814472b3
#2 [ffff8802244c3d28] rt_mutex_slowlock at ffffffff814473f5
#3 [ffff8802244c3dc8] reiserfs_write_lock at ffffffffa05f28fd [reiserfs]
#4 [ffff8802244c3de8] flush_async_commits at ffffffffa05ec91d [reiserfs]
#5 [ffff8802244c3e08] process_one_work at ffffffff81073726
#6 [ffff8802244c3e68] worker_thread at ffffffff81073eba
#7 [ffff8802244c3ec8] kthread at ffffffff810782e0
#8 [ffff8802244c3f48] kernel_thread_helper at ffffffff81450064
crash> rd ffff8802244c3cc8 10
ffff8802244c3cc8: ffffffff814472b3 ffff880222f23250 .rD.....P2."....
ffff8802244c3cd8: 0000000000000000 0000000000000286 ................
ffff8802244c3ce8: ffff8802244c3d30 ffff880220734d80 0=L$.....Ms ....
ffff8802244c3cf8: ffff880222e8f628 0000000000000000 (.."............
ffff8802244c3d08: 0000000000000000 0000000000000002 ................
crash> struct rt_mutex ffff880222e8f628
struct rt_mutex {
wait_lock = {
raw_lock = {
slock = 65537
}
},
wait_list = {
node_list = {
next = 0xffff8802244c3d48,
prev = 0xffff8802244c3d48
}
},
owner = 0xffff880222f22c71,
save_state = 0
}
crash> bt 0xffff880222f22c70
PID: 10635 TASK: ffff880222f22c70 CPU: 3 COMMAND: "mount"
#0 [ffff8802216a9868] schedule at ffffffff8144584b
#1 [ffff8802216a9910] schedule_timeout at ffffffff81446865
#2 [ffff8802216a99a0] wait_for_common at ffffffff81445f74
#3 [ffff8802216a9a30] flush_work at ffffffff810712d3
#4 [ffff8802216a9ab0] schedule_on_each_cpu at ffffffff81074463
#5 [ffff8802216a9ae0] invalidate_bdev at ffffffff81178aba
#6 [ffff8802216a9af0] vfs_load_quota_inode at ffffffff811a3632
#7 [ffff8802216a9b50] dquot_quota_on_mount at ffffffff811a375c
#8 [ffff8802216a9b80] finish_unfinished at ffffffffa05dd8b0 [reiserfs]
#9 [ffff8802216a9cc0] reiserfs_fill_super at ffffffffa05de825 [reiserfs]
#10 [ffff8802216a9d90] mount_bdev at ffffffff8114c93f
#11 [ffff8802216a9e00] mount_fs at ffffffff8114d035
#12 [ffff8802216a9e50] vfs_kern_mount at ffffffff81167d36
#13 [ffff8802216a9e90] do_kern_mount at ffffffff811692c3
#14 [ffff8802216a9ed0] do_mount at ffffffff8116adb5
#15 [ffff8802216a9f30] sys_mount at ffffffff8116b25a
#16 [ffff8802216a9f80] system_call_fastpath at ffffffff8144ef12
RIP: 00007f7b9303997a RSP: 00007ffff443c7a8 RFLAGS: 00010202
RAX: 00000000000000a5 RBX: ffffffff8144ef12 RCX: 00007f7b932e9ee0
RDX: 00007f7b93d9a400 RSI: 00007f7b93d9a3e0 RDI: 00007f7b93d9a3c0
RBP: 00007f7b93d9a2c0 R8: 00007f7b93d9a550 R9: 0000000000000001
R10: ffffffffc0ed040e R11: 0000000000000202 R12: 000000000000040e
R13: 0000000000000000 R14: 00000000c0ed040e R15: 00007ffff443ca20
ORIG_RAX: 00000000000000a5 CS: 0033 SS: 002b
Signed-off-by: Mike Galbraith <efault@gmx.de>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: <stable@vger.kernel.org>
---
fs/reiserfs/super.c | 12 +++++++++++-
1 files changed, 11 insertions(+), 1 deletions(-)
diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c
index 7a37dab..50635a9 100644
--- a/fs/reiserfs/super.c
+++ b/fs/reiserfs/super.c
@@ -184,7 +184,15 @@ static int remove_save_link_only(struct super_block *s,
static int reiserfs_quota_on_mount(struct super_block *, int);
#endif
-/* look for uncompleted unlinks and truncates and complete them */
+/*
+ *look for uncompleted unlinks and truncates and complete them
+ *
+ * Called with superblock write locked. If quotas are enabled,
+ * we have to release/retake lest we call dquot_quota_on_mount(),
+ * proceed to schedule_on_each_cpu() and deadlock waiting for
+ * the per cpu worklets to complete flush_async_commits() that
+ * in turn wait for the superblock write lock.
+ */
static int finish_unfinished(struct super_block *s)
{
INITIALIZE_PATH(path);
@@ -231,7 +239,9 @@ static int finish_unfinished(struct super_block *s)
quota_enabled[i] = 0;
continue;
}
+ reiserfs_write_unlock(s);
ret = reiserfs_quota_on_mount(s, i);
+ reiserfs_write_lock(s);
if (ret < 0)
reiserfs_warning(s, "reiserfs-2500",
"cannot turn on journaled "
^ permalink raw reply related [flat|nested] 12+ messages in thread
end of thread, other threads:[~2012-08-16 13:49 UTC | newest]
Thread overview: 12+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2012-08-14 13:06 [rfc patch] fs,reiserfs: unlock superblock before callling reiserfs_quota_on_mount() Mike Galbraith
2012-08-14 14:23 ` Steven Rostedt
2012-08-14 14:39 ` Mike Galbraith
2012-08-14 14:56 ` Mike Galbraith
2012-08-14 15:18 ` Thomas Gleixner
2012-08-14 17:26 ` Mike Galbraith
2012-08-14 17:44 ` Steven Rostedt
2012-08-14 18:09 ` Mike Galbraith
2012-08-14 15:15 ` Frederic Weisbecker
2012-08-16 12:44 ` [patch] " Mike Galbraith
2012-08-16 13:05 ` Frederic Weisbecker
2012-08-16 13:49 ` Mike Galbraith
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