lkml.org 
[lkml]   [2022]   [Jan]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: INFO: task hung in add_transaction_credits
Hello!

On Tue 04-01-22 18:30:47, kvartet wrote:
> When using Syzkaller to fuzz the latest Linux kernel, the following
> crash was triggered.
>
> HEAD commit: a7904a538933 Linux 5.16-rc6
> git tree: upstream
> console output: https://paste.ubuntu.com/p/N2WMbfsc5s/plain/
> kernel config: https://paste.ubuntu.com/p/FDDNHDxtwz/plain/
>
> Sorry, I don't have a reproducer for this crash, hope the symbolized
> report can help.
>
> If you fix this issue, please add the following tag to the commit:
> Reported-by: Yiru Xu <xyru1999@gmail.com>

Thanks for report. I had a look into the stacktraces. What is clear is that
there are several processes waiting in wait_transaction_locked() meaning
that we want to commit a transaction and wait while there are still active
handles attached to the transaction. I can also infer that the process
holding the handle for the transaction is:

4 locks held by syz-executor.1/20606:
#0: ffff88810c7ec460 (sb_writers#5){.+.+}-{0:0}, at:
filename_create+0xf3/0x490 fs/namei.c:3649
#1: ffff888028ff7198 (&type->i_mutex_dir_key#4/1){+.+.}-{3:3}, at:
inode_lock_nested include/linux/fs.h:818 [inline]
#1: ffff888028ff7198 (&type->i_mutex_dir_key#4/1){+.+.}-{3:3}, at:
filename_create+0x158/0x490 fs/namei.c:3654
#2: ffff88810c7f8990 (jbd2_handle){++++}-{0:0}, at:
start_this_handle+0xf58/0x1360 fs/jbd2/transaction.c:466
#3: ffff8880287f2e28 (&mapping->i_mmap_rwsem){++++}-{3:3}, at:
i_mmap_lock_read include/linux/fs.h:513 [inline]
#3: ffff8880287f2e28 (&mapping->i_mmap_rwsem){++++}-{3:3}, at:
rmap_walk_file+0x86d/0xc20 mm/rmap.c:2345

What is not obvious though is why this task is blocked and does not
eventually release the transaction handle. For that we would need a
stacktrace of this task...

Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR

\
 
 \ /
  Last update: 2022-01-06 16:46    [W:0.056 / U:0.084 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site