On Fri, Jul 23, 2021 at 09:51:09AM +0800, Miaohe Lin wrote:

On 2021/7/22 22:00, Greg KH wrote:

quoted

On Thu, Jul 22, 2021 at 03:26:52PM +0200, Greg KH wrote:

quoted

On Thu, Jul 22, 2021 at 01:36:02PM +0100, Matthew Wilcox wrote:

quoted

On Thu, Jul 22, 2021 at 04:57:57PM +0800, Zhouyi Zhou wrote:

quoted

Thanks for reviewing,

What I have deduced from the dmesg  is:
In function do_swap_page,
after invoking
3385        si = get_swap_device(entry); /* rcu_read_lock */
and before
3561    out:
3562        if (si)
3563            put_swap_device(si);
The thread got scheduled out in
3454        locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);

I am only familiar with Linux RCU subsystem, hope mm people can solve our
confusions.

I don't understamd why you're still talking.  The problem is understood.
You need to revert the unnecessary backport of 2799e77529c2 and
2efa33fc7f6e

Sorry for the delay, will go do so in a minute...

Both now reverted from 5.10.y and 5.13.y.

I browsed my previous backport notifying email and found that these two patches are also
backported into 5.12. And it seems it's missed.

5.12 is now end-of-life, it's not being touched anymore, and no one
should continue to use it.

thanks,

greg k-h