Re: [PATCH] slub: fix unreclaimable slab stat for bulk free

From: Kefeng Wang
Date: Tue Aug 03 2021 - 10:45:20 EST

On 2021/8/3 22:29, Vlastimil Babka wrote:
On 8/3/21 4:24 PM, Kefeng Wang wrote:
On 2021/7/29 22:03, Shakeel Butt wrote:
On Wed, Jul 28, 2021 at 11:52 PM Kefeng Wang <> wrote:
On 2021/7/28 23:53, Shakeel Butt wrote:
I don't have a strong opinion on this. Please send a patch with
reasoning if you want WARN_ON_ONCE here.
Ok, we met a BUG_ON(!PageCompound(page)) in kfree() twice in lts4.4, we are
still debugging it.

It's different to analyses due to no vmcore, and can't be reproduced.

WARN_ON() here could help us to notice the issue.

Also is there any experience or known fix/way to debug this kinds of issue?
memory corruption?
This would typically be a use-after-free/double-free - a problem of the slab
user, not slab itself.

We enable KASAN to find whether or not there are some UAF/double free, no related

log for now.

Any suggestion will be appreciated, thanks.
debug_pagealloc could help to catch a use-after-free earlier

OK, will try this, thanks.