On 9/27/18 11:53 PM, Eddie Chapman wrote:
On 27/09/18 16:23, Coly Li wrote:
On 9/27/18 9:45 PM, guoju wrote:
After write SSD completed, bcache schedule journal_write work to
system_wq, that is a public workqueue in system, without WQ_MEM_RECLAIM
flag. system_wq is also a bound wq, and there may be no idle kworker on
current processor. Creating a new kworker may unfortunately need to
reclaim memory first, by shrinking cache and slab used by vfs, which
depends on bcache device. That's a deadlock.
This patch create a new workqueue for journal_write with WQ_MEM_RECLAIM
flag. It's rescuer thread will work to avoid the deadlock.
Signed-off-by: guoju <fangguoju@xxxxxxxxx>
Nice catch, this fix is quite important. I will try to submit to Jens
ASAP.
Thanks.
Coly Li
Once this goes into 4.19, would this be a candidate for backporting to
any stable kernels, or does it only fix something introduced in this
cycle?
This bug exists in upstream for quite long time, it should be applied to
all stable kernels which it can be applied. And it is Cced to
stable@xxxxxxxxxxxxxxx already.
Coly Li
