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Groups > linux.kernel > #1335700
| From | Tejun Heo <tj@kernel.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH block/for-4.5-fixes] writeback: keep superblock pinned during cgroup writeback association switches |
| Date | 2016-02-16 19:30 +0100 |
| Message-ID | <r2SxQ-35i-7@gated-at.bofh.it> (permalink) |
| References | <r2SxQ-35i-9@gated-at.bofh.it> <r2SxQ-35i-11@gated-at.bofh.it> <r2SxQ-35i-13@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
From 586afaa034bec88934bad4eb6ab38ba07031ec5a Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Tue, 16 Feb 2016 13:14:35 -0500
If cgroup writeback is in use, an inode is associated with a cgroup
for writeback. If the inode's main dirtier changes to another cgroup,
the association gets updated asynchronously. Nothing was pinning the
superblock while such switches are in progress and superblock could go
away while async switching is pending or in progress leading to
crashes like the following.
kernel BUG at fs/jbd2/transaction.c:319!
invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC
CPU: 1 PID: 29158 Comm: kworker/1:10 Not tainted 4.5.0-rc3 #51
Hardware name: Google Google, BIOS Google 01/01/2011
Workqueue: events inode_switch_wbs_work_fn
task: ffff880213dbbd40 ti: ffff880209264000 task.ti: ffff880209264000
RIP: 0010:[<ffffffff803e6922>] [<ffffffff803e6922>] start_this_handle+0x382/0x3e0
RSP: 0018:ffff880209267c30 EFLAGS: 00010202
...
Call Trace:
[<ffffffff803e6be4>] jbd2__journal_start+0xf4/0x190
[<ffffffff803cfc7e>] __ext4_journal_start_sb+0x4e/0x70
[<ffffffff803b31ec>] ext4_evict_inode+0x12c/0x3d0
[<ffffffff8035338b>] evict+0xbb/0x190
[<ffffffff80354190>] iput+0x130/0x190
[<ffffffff80360223>] inode_switch_wbs_work_fn+0x343/0x4c0
[<ffffffff80279819>] process_one_work+0x129/0x300
[<ffffffff80279b16>] worker_thread+0x126/0x480
[<ffffffff8027ed14>] kthread+0xc4/0xe0
[<ffffffff809771df>] ret_from_fork+0x3f/0x70
Fix it by bumping s_active while cgroup association switching is in
flight.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-and-tested-by: Tahsin Erdogan <tahsin@google.com>
Link: http://lkml.kernel.org/g/CAAeU0aNCq7LGODvVGRU-oU_o-6enii5ey0p1c26D1ZzYwkDc5A@mail.gmail.com
Fixes: d10c80955265 ("writeback: implement foreign cgroup inode bdi_writeback switching")
Cc: stable@vger.kernel.org #v4.5+
---
fs/fs-writeback.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 6915c95..1f76d89 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -317,6 +317,7 @@ static void inode_switch_wbs_work_fn(struct work_struct *work)
struct inode_switch_wbs_context *isw =
container_of(work, struct inode_switch_wbs_context, work);
struct inode *inode = isw->inode;
+ struct super_block *sb = inode->i_sb;
struct address_space *mapping = inode->i_mapping;
struct bdi_writeback *old_wb = inode->i_wb;
struct bdi_writeback *new_wb = isw->new_wb;
@@ -423,6 +424,7 @@ static void inode_switch_wbs_work_fn(struct work_struct *work)
wb_put(new_wb);
iput(inode);
+ deactivate_super(sb);
kfree(isw);
}
@@ -469,11 +471,14 @@ static void inode_switch_wbs(struct inode *inode, int new_wb_id)
/* while holding I_WB_SWITCH, no one else can update the association */
spin_lock(&inode->i_lock);
+
if (inode->i_state & (I_WB_SWITCH | I_FREEING) ||
- inode_to_wb(inode) == isw->new_wb) {
- spin_unlock(&inode->i_lock);
- goto out_free;
- }
+ inode_to_wb(inode) == isw->new_wb)
+ goto out_unlock;
+
+ if (!atomic_inc_not_zero(&inode->i_sb->s_active))
+ goto out_unlock;
+
inode->i_state |= I_WB_SWITCH;
spin_unlock(&inode->i_lock);
@@ -489,6 +494,8 @@ static void inode_switch_wbs(struct inode *inode, int new_wb_id)
call_rcu(&isw->rcu_head, inode_switch_wbs_rcu_fn);
return;
+out_unlock:
+ spin_unlock(&inode->i_lock);
out_free:
if (isw->new_wb)
wb_put(isw->new_wb);
--
2.5.0
Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread
[PATCH block/for-4.5-fixes] writeback: keep superblock pinned during cgroup writeback association switches Tejun Heo <tj@kernel.org> - 2016-02-16 19:30 +0100
Re: [PATCH block/for-4.5-fixes] writeback: keep superblock pinned during cgroup writeback association switches Jens Axboe <axboe@kernel.dk> - 2016-02-16 19:40 +0100
Re: [PATCH block/for-4.5-fixes] writeback: keep superblock pinned during cgroup writeback association switches Jan Kara <jack@suse.cz> - 2016-02-17 22:00 +0100
Re: [PATCH block/for-4.5-fixes] writeback: keep superblock pinned during cgroup writeback association switches Tejun Heo <tj@kernel.org> - 2016-02-17 22:10 +0100
Re: [PATCH block/for-4.5-fixes] writeback: keep superblock pinned during cgroup writeback association switches Jan Kara <jack@suse.cz> - 2016-02-17 23:30 +0100
Re: [PATCH block/for-4.5-fixes] writeback: keep superblock pinned during cgroup writeback association switches Tahsin Erdogan <tahsin@google.com> - 2016-02-17 23:50 +0100
Re: [PATCH block/for-4.5-fixes] writeback: keep superblock pinned during cgroup writeback association switches Tejun Heo <tj@kernel.org> - 2016-02-18 00:10 +0100
Re: [PATCH block/for-4.5-fixes] writeback: keep superblock pinned during cgroup writeback association switches Jan Kara <jack@suse.cz> - 2016-02-18 11:00 +0100
Re: [PATCH block/for-4.5-fixes] writeback: keep superblock pinned during cgroup writeback association switches Tejun Heo <tj@kernel.org> - 2016-02-18 14:10 +0100
Re: [PATCH block/for-4.5-fixes] writeback: keep superblock pinned during cgroup writeback association switches Jan Kara <jack@suse.cz> - 2016-02-18 14:30 +0100
Re: [PATCH block/for-4.5-fixes] writeback: keep superblock pinned during cgroup writeback association switches Al Viro <viro@ZenIV.linux.org.uk> - 2016-02-19 21:20 +0100
Re: [PATCH block/for-4.5-fixes] writeback: keep superblock pinned during cgroup writeback association switches Tejun Heo <tj@kernel.org> - 2016-02-19 22:00 +0100
Re: [PATCH block/for-4.5-fixes] writeback: keep superblock pinned during cgroup writeback association switches Al Viro <viro@ZenIV.linux.org.uk> - 2016-02-19 23:00 +0100
Re: [PATCH block/for-4.5-fixes] writeback: keep superblock pinned during cgroup writeback association switches Tejun Heo <tj@kernel.org> - 2016-02-19 23:20 +0100
Re: [PATCH block/for-4.5-fixes] writeback: keep superblock pinned during cgroup writeback association switches Al Viro <viro@ZenIV.linux.org.uk> - 2016-02-19 23:30 +0100
Re: [PATCH block/for-4.5-fixes] writeback: keep superblock pinned during cgroup writeback association switches Nikolay Borisov <kernel@kyup.com> - 2016-02-18 11:20 +0100
Re: [PATCH block/for-4.5-fixes] writeback: keep superblock pinned during cgroup writeback association switches Tejun Heo <tj@kernel.org> - 2016-02-18 14:00 +0100
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