Re: How to handle TIF_MEMDIE stalls?

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Thu 19-02-15 19:48:16, Tetsuo Handa wrote:
> Michal Hocko wrote:
[...]
> > I do not understand. What kind of bug would be fixed by that change?
> 
> That change fixes significant loss of file I/O reliability under extreme
> memory pressure.
> 
> Today I tested how frequent filesystem errors occurs using scripted environment.
> ( Source code of a.out is http://marc.info/?l=linux-fsdevel&m=142425860904849&w=2 )
> 
> ----------
> #!/bin/sh
> : > ~/trial.log
> for i in `seq 1 100`
> do
>     mkfs.ext4 -q /dev/sdb1 || exit 1
>     mount -o errors=remount-ro /dev/sdb1 /tmp || exit 2
>     chmod 1777 /tmp
>     su - demo -c ~demo/a.out
>     if [ -w /tmp/ ]
>     then
>         echo -n "S" >> ~/trial.log
>     else
>         echo -n "F" >> ~/trial.log
>     fi
>     umount /tmp
> done
> ----------
> 
> We can see that filesystem errors are occurring frequently if GFP_NOFS / GFP_NOIO
> allocations give up without retrying.

I would suggest reporting this to ext people (in a separate thread
please) and see what is the proper fix.

> On the other hand, as far as these trials,
> TIF_MEMDIE stall was not observed if GFP_NOFS / GFP_NOIO allocations give up
> without retrying. Maybe giving up without retrying is keeping away from hitting
> stalls for this test case?

This is expected because those allocations are with locks held and so
the chances to release the lock are higher.

[...]
-- 
Michal Hocko
SUSE Labs
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [Samba]     [Device Mapper]     [CEPH Development]
  Powered by Linux