linux-kernel - Re: [REGRESSION] BUG: KFENCE: memory corruption in drm_gem_put

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Message-ID: <3254850.aeNJFYEL58@natalenko.name>
Date:   Thu, 05 Oct 2023 09:56:03 +0200
From:   Oleksandr Natalenko <oleksandr@...alenko.name>
To:     Matthew Wilcox <willy@...radead.org>,
        Thomas Zimmermann <tzimmermann@...e.de>
Cc:     Linux Regressions <regressions@...ts.linux.dev>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        Christian König <christian.koenig@....com>,
        linaro-mm-sig@...ts.linaro.org, linux-mm@...ck.org,
        Maxime Ripard <mripard@...nel.org>,
        Bagas Sanjaya <bagasdotme@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        linux-media@...r.kernel.org
Subject: Re: [REGRESSION] BUG: KFENCE: memory corruption in
 drm_gem_put_pages+0x186/0x250

Hello.

On čtvrtek 5. října 2023 9:44:42 CEST Thomas Zimmermann wrote:
> Hi
> 
> Am 02.10.23 um 17:38 schrieb Oleksandr Natalenko:
> > On pondělí 2. října 2023 16:32:45 CEST Matthew Wilcox wrote:
> >> On Mon, Oct 02, 2023 at 01:02:52PM +0200, Oleksandr Natalenko wrote:
> >>>>>>> BUG: KFENCE: memory corruption in drm_gem_put_pages+0x186/0x250
> >>>>>>>
> >>>>>>> Corrupted memory at 0x00000000e173a294 [ ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ] (in kfence-#108):
> >>>>>>>   drm_gem_put_pages+0x186/0x250
> >>>>>>>   drm_gem_shmem_put_pages_locked+0x43/0xc0
> >>>>>>>   drm_gem_shmem_object_vunmap+0x83/0xe0
> >>>>>>>   drm_gem_vunmap_unlocked+0x46/0xb0
> >>>>>>>   drm_fbdev_generic_helper_fb_dirty+0x1dc/0x310
> >>>>>>>   drm_fb_helper_damage_work+0x96/0x170
> >>>
> >>> Matthew, before I start dancing around, do you think ^^ could have the same cause as 0b62af28f249b9c4036a05acfb053058dc02e2e2 which got fixed by 863a8eb3f27098b42772f668e3977ff4cae10b04?
> >>
> >> Yes, entirely plausible.  I think you have two useful points to look at
> >> before delving into a full bisect -- 863a8e and the parent of 0b62af.
> >> If either of them work, I think you have no more work to do.
> > 
> > OK, I've did this against v6.5.5:
> > 
> > ```
> > git log --oneline HEAD~3..
> > 7c1e7695ca9b8 (HEAD -> test) Revert "mm: remove struct pagevec"
> > 8f2ad53b6eac6 Revert "mm: remove check_move_unevictable_pages()"
> > fa1e3c0b5453c Revert "drm: convert drm_gem_put_pages() to use a folio_batch"
> > ```
> > 
> > then rebooted the host multiple times, and the issue is not seen any more.
> > 
> > So I guess 3291e09a463870610b8227f32b16b19a587edf33 is the culprit.
> 
> Ignore my other email. It's apparently been fixed already. Thanks!

Has it? I think I was able to identify offending commit, but I'm not aware of any fix to that.

Thanks.

> Best regards
> Thomas
> 
> > 
> > Thanks.
> > 
> 
> -- 
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Frankenstrasse 146, 90461 Nuernberg, Germany
> GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
> HRB 36809 (AG Nuernberg)
> 


-- 
Oleksandr Natalenko (post-factum)
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