* [PATCH] btrfs: Fix rcu_dereference usage outside of read critical section
@ 2018-02-20 11:40 Nikolay Borisov
2018-02-20 12:44 ` Anand Jain
0 siblings, 1 reply; 3+ messages in thread
From: Nikolay Borisov @ 2018-02-20 11:40 UTC (permalink / raw)
To: linux-btrfs; +Cc: dsterba, anand.jain, Nikolay Borisov
Patch 11ac3f1da5fd ("btrfs: log, when replace, is canceled by the user")
added a new btrfs_info call with a couple of btrfs_dev_name() args. This
is wrong since the latter require being called in rcu read side
critical section. Fix it by instead calling btrfs_info_in_rcu. This
fixes the following splat:
=============================
WARNING: suspicious RCU usage
4.16.0-rc2-nbor #463 Not tainted
-----------------------------
fs/btrfs/dev-replace.c:318 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
1 lock held by btrfs/5698:
#0: (&fs_info->dev_replace.lock_finishing_cancel_unmount){+.+.}, at: [<00000000942cb4ee>] btrfs_dev_replace_cancel+0xac/0x3f0
stack backtrace:
CPU: 2 PID: 5698 Comm: btrfs Not tainted 4.16.0-rc2-nbor #463
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
Call Trace:
dump_stack+0x85/0xc9
lockdep_rcu_suspicious+0x123/0x170
btrfs_dev_name.part.1+0x6d/0x80
btrfs_dev_replace_cancel+0x330/0x3f0
btrfs_ioctl+0x2751/0x65b0
? debug_check_no_locks_freed+0x290/0x290
? trace_hardirqs_on_caller+0x400/0x570
? trace_hardirqs_on+0xd/0x10
? btrfs_ioctl_get_supported_features+0x30/0x30
? __handle_mm_fault+0x1aca/0x3230
? lock_downgrade+0x650/0x650
? trace_hardirqs_on+0xd/0x10
? mem_cgroup_commit_charge+0xc0/0xdd0
? _raw_spin_unlock+0x27/0x40
? __handle_mm_fault+0x1aca/0x3230
? lock_downgrade+0x650/0x650
? vm_insert_page+0x650/0x650
? __vma_link_rb+0x125/0x1d0
do_vfs_ioctl+0x184/0xf00
? do_vfs_ioctl+0x184/0xf00
? lock_downgrade+0x650/0x650
? ioctl_preallocate+0x1a0/0x1a0
? up_read+0x1f/0x40
? __do_page_fault+0x5c6/0xb30
? SyS_brk+0x412/0x5f0
? mm_fault_error+0x2e0/0x2e0
SyS_ioctl+0x41/0x70
? do_vfs_ioctl+0xf00/0xf00
do_syscall_64+0x19d/0x5d0
entry_SYSCALL_64_after_hwframe+0x42/0xb7
Fixes: 11ac3f1da5fd ("btrfs: log, when replace, is canceled by the user")
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
---
fs/btrfs/dev-replace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 3b0760f7ec8a..0e776eb90ad8 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -744,7 +744,7 @@ int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
ret = btrfs_commit_transaction(trans);
WARN_ON(ret);
- btrfs_info(fs_info, "dev_replace from %s (devid %llu) to %s canceled",
+ btrfs_info_in_rcu(fs_info, "dev_replace from %s (devid %llu) to %s cancelled",
btrfs_dev_name(src_device), src_device->devid,
btrfs_dev_name(tgt_device));
--
2.7.4
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] btrfs: Fix rcu_dereference usage outside of read critical section
2018-02-20 11:40 [PATCH] btrfs: Fix rcu_dereference usage outside of read critical section Nikolay Borisov
@ 2018-02-20 12:44 ` Anand Jain
2018-02-21 20:07 ` David Sterba
0 siblings, 1 reply; 3+ messages in thread
From: Anand Jain @ 2018-02-20 12:44 UTC (permalink / raw)
To: Nikolay Borisov, linux-btrfs; +Cc: dsterba
On 02/20/2018 07:40 PM, Nikolay Borisov wrote:
> Patch 11ac3f1da5fd ("btrfs: log, when replace, is canceled by the user")
> added a new btrfs_info call with a couple of btrfs_dev_name() args. This
> is wrong since the latter require being called in rcu read side
> critical section. Fix it by instead calling btrfs_info_in_rcu. This
> fixes the following splat:
>
> =============================
> WARNING: suspicious RCU usage
> 4.16.0-rc2-nbor #463 Not tainted
> -----------------------------
> fs/btrfs/dev-replace.c:318 suspicious rcu_dereference_check() usage!
>
> other info that might help us debug this:
>
> rcu_scheduler_active = 2, debug_locks = 1
> 1 lock held by btrfs/5698:
> #0: (&fs_info->dev_replace.lock_finishing_cancel_unmount){+.+.}, at: [<00000000942cb4ee>] btrfs_dev_replace_cancel+0xac/0x3f0
>
> stack backtrace:
> CPU: 2 PID: 5698 Comm: btrfs Not tainted 4.16.0-rc2-nbor #463
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
> Call Trace:
> dump_stack+0x85/0xc9
> lockdep_rcu_suspicious+0x123/0x170
> btrfs_dev_name.part.1+0x6d/0x80
> btrfs_dev_replace_cancel+0x330/0x3f0
> btrfs_ioctl+0x2751/0x65b0
> ? debug_check_no_locks_freed+0x290/0x290
> ? trace_hardirqs_on_caller+0x400/0x570
> ? trace_hardirqs_on+0xd/0x10
> ? btrfs_ioctl_get_supported_features+0x30/0x30
> ? __handle_mm_fault+0x1aca/0x3230
> ? lock_downgrade+0x650/0x650
> ? trace_hardirqs_on+0xd/0x10
> ? mem_cgroup_commit_charge+0xc0/0xdd0
> ? _raw_spin_unlock+0x27/0x40
> ? __handle_mm_fault+0x1aca/0x3230
> ? lock_downgrade+0x650/0x650
> ? vm_insert_page+0x650/0x650
> ? __vma_link_rb+0x125/0x1d0
> do_vfs_ioctl+0x184/0xf00
> ? do_vfs_ioctl+0x184/0xf00
> ? lock_downgrade+0x650/0x650
> ? ioctl_preallocate+0x1a0/0x1a0
> ? up_read+0x1f/0x40
> ? __do_page_fault+0x5c6/0xb30
> ? SyS_brk+0x412/0x5f0
> ? mm_fault_error+0x2e0/0x2e0
> SyS_ioctl+0x41/0x70
> ? do_vfs_ioctl+0xf00/0xf00
> do_syscall_64+0x19d/0x5d0
> entry_SYSCALL_64_after_hwframe+0x42/0xb7
>
> Fixes: 11ac3f1da5fd ("btrfs: log, when replace, is canceled by the user")
> Signed-off-by: Nikolay Borisov <nborisov@suse.com>
I notice too. Thanks Nikolay for the fix.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
> ---
> fs/btrfs/dev-replace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
> index 3b0760f7ec8a..0e776eb90ad8 100644
> --- a/fs/btrfs/dev-replace.c
> +++ b/fs/btrfs/dev-replace.c
> @@ -744,7 +744,7 @@ int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
> ret = btrfs_commit_transaction(trans);
> WARN_ON(ret);
>
> - btrfs_info(fs_info, "dev_replace from %s (devid %llu) to %s canceled",
> + btrfs_info_in_rcu(fs_info, "dev_replace from %s (devid %llu) to %s cancelled",
> btrfs_dev_name(src_device), src_device->devid,
> btrfs_dev_name(tgt_device));
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] btrfs: Fix rcu_dereference usage outside of read critical section
2018-02-20 12:44 ` Anand Jain
@ 2018-02-21 20:07 ` David Sterba
0 siblings, 0 replies; 3+ messages in thread
From: David Sterba @ 2018-02-21 20:07 UTC (permalink / raw)
To: Anand Jain; +Cc: Nikolay Borisov, linux-btrfs, dsterba
On Tue, Feb 20, 2018 at 08:44:57PM +0800, Anand Jain wrote:
>
>
> On 02/20/2018 07:40 PM, Nikolay Borisov wrote:
> > Patch 11ac3f1da5fd ("btrfs: log, when replace, is canceled by the user")
> > added a new btrfs_info call with a couple of btrfs_dev_name() args. This
> > is wrong since the latter require being called in rcu read side
> > critical section. Fix it by instead calling btrfs_info_in_rcu. This
> > fixes the following splat:
> >
> > =============================
> > WARNING: suspicious RCU usage
> > 4.16.0-rc2-nbor #463 Not tainted
> > -----------------------------
> > fs/btrfs/dev-replace.c:318 suspicious rcu_dereference_check() usage!
> >
> > other info that might help us debug this:
> >
> > rcu_scheduler_active = 2, debug_locks = 1
> > 1 lock held by btrfs/5698:
> > #0: (&fs_info->dev_replace.lock_finishing_cancel_unmount){+.+.}, at: [<00000000942cb4ee>] btrfs_dev_replace_cancel+0xac/0x3f0
> >
> > stack backtrace:
> > CPU: 2 PID: 5698 Comm: btrfs Not tainted 4.16.0-rc2-nbor #463
> > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
> > Call Trace:
> > dump_stack+0x85/0xc9
> > lockdep_rcu_suspicious+0x123/0x170
> > btrfs_dev_name.part.1+0x6d/0x80
> > btrfs_dev_replace_cancel+0x330/0x3f0
> > btrfs_ioctl+0x2751/0x65b0
> > ? debug_check_no_locks_freed+0x290/0x290
> > ? trace_hardirqs_on_caller+0x400/0x570
> > ? trace_hardirqs_on+0xd/0x10
> > ? btrfs_ioctl_get_supported_features+0x30/0x30
> > ? __handle_mm_fault+0x1aca/0x3230
> > ? lock_downgrade+0x650/0x650
> > ? trace_hardirqs_on+0xd/0x10
> > ? mem_cgroup_commit_charge+0xc0/0xdd0
> > ? _raw_spin_unlock+0x27/0x40
> > ? __handle_mm_fault+0x1aca/0x3230
> > ? lock_downgrade+0x650/0x650
> > ? vm_insert_page+0x650/0x650
> > ? __vma_link_rb+0x125/0x1d0
> > do_vfs_ioctl+0x184/0xf00
> > ? do_vfs_ioctl+0x184/0xf00
> > ? lock_downgrade+0x650/0x650
> > ? ioctl_preallocate+0x1a0/0x1a0
> > ? up_read+0x1f/0x40
> > ? __do_page_fault+0x5c6/0xb30
> > ? SyS_brk+0x412/0x5f0
> > ? mm_fault_error+0x2e0/0x2e0
> > SyS_ioctl+0x41/0x70
> > ? do_vfs_ioctl+0xf00/0xf00
> > do_syscall_64+0x19d/0x5d0
> > entry_SYSCALL_64_after_hwframe+0x42/0xb7
> >
> > Fixes: 11ac3f1da5fd ("btrfs: log, when replace, is canceled by the user")
> > Signed-off-by: Nikolay Borisov <nborisov@suse.com>
>
> I notice too. Thanks Nikolay for the fix.
I'll fold the fix into the original patch.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2018-02-21 20:10 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2018-02-20 11:40 [PATCH] btrfs: Fix rcu_dereference usage outside of read critical section Nikolay Borisov
2018-02-20 12:44 ` Anand Jain
2018-02-21 20:07 ` David Sterba
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).