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From: Shakeel Butt To: Andrew Morton Cc: Deepanshu Kartikey , syzbot , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@kernel.org, roman.gushchin@linux.dev, syzkaller-bugs@googlegroups.com, Johannes Weiner , Muchun Song , Minchan Kim Subject: Re: [syzbot] [cgroups?] [mm?] WARNING in memcg1_swapout Message-ID: References: <696b56b1.050a0220.3390f1.0007.GAE@google.com> <20260117165722.6dc25d72fd58254cb89e711b@linux-foundation.org> <20260118125311.e1894f598e2a8ef626f47f25@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260118125311.e1894f598e2a8ef626f47f25@linux-foundation.org> X-Migadu-Flow: FLOW_OUT X-Stat-Signature: dkg9y7pxewaynpk9yq7ma8x8gqmz9kij X-Rspamd-Queue-Id: DD10EC0006 X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1768944054-566826 X-HE-Meta: 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 NYhOcK8u mfkV9qjIdVoWJ9IoR9ttHaCGqf4GbYL1pAjYG5MK7CIlI2WT8wiU/aHt1cw2GgLeo16F6uekiNxgCphBKpH8zmV1dWl45C4D4U69XQ79PZpYJ/JX6wK7UgOMEgzj0VpFxI9EA/mSUdiNUXzpL6r8XeZ0nKWDS+fsVWbM2p6OIiPxGBtFs/ingdEuV3mwMgm2gtqGJC6vi1CRPQgHjHpDza91Ez4V/vBAySBXYfC7Tarho06SCHPwLxovuFXeQYPY/gmOIg6JU12vnqrXdAswMFbNoA+ift/3T1YKwKGE4bImso+PgjnyYvVGnxIYgoUGW6n7hGsjOXQ0TZuG4mlWqPVAD5XXS9EBAmQIa9VqLrlrmuhcSUxFYS3jHeOyAOzGibaypvLeqgvIy25tRax8TR4Dbkly9Et5uk4xTynCzVGYV2kOQqUMTMEq86RVTqw2LZCLt X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, Jan 18, 2026 at 12:53:11PM -0800, Andrew Morton wrote: > On Sun, 18 Jan 2026 12:31:43 +0530 Deepanshu Kartikey wrote: > > > > > > > > > That's > > > > > > > > VM_WARN_ON_ONCE(oldid != 0); > > > > > > > > which was added by Deepanshu's "mm/swap_cgroup: fix kernel BUG in > > > > swap_cgroup_record". > > > > > > > > This patch has Fixes: 1a4e58cce84e ("mm: introduce MADV_PAGEOUT"), > > > > which is six years old. For some reason it has no cc:stable. > > > > > > > > Deepanshu's patch has no reviews. > > > > > > > > So can I please do the memcg maintainer summoning dance here? We have a > > > > repeatable BUG happening in mainline Linux. > > > > > > > > > > Hi Andrew, > > > > > > I checked the git blame output for commit 0f853ca2a798: > > > > > > Line 763: memcg1_swapout(folio, swap); > > > Line 764: __swap_cache_del_folio(ci, folio, swap, shadow); > > > (d7a7b2f91f36b - Kairui Song, 2026-01-13 02:33:36 +0800) > > > > > > Kairui's reordering patch appears to have been merged on Jan 13. > > Eek, there are many patches, it helps to identify them carefully. > > I think you're referring to > https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-swap-use-swap-cache-as-the-swap-in-synchronize-layer-fix.patch > > > > The syzbot report is also from Jan 13, likely from earlier in the > > > day before the reordering patch was merged. > > > > > > So this report is from before the fix. The warning should not appear > > > in linux-next builds after Jan 13. > > > > > > Thanks, > > > > > > Deepanshu > > > > Hi Andrew, > > > > I tested with the latest linux-next in sysbot. It is working fine > > Great, thanks. But we still don't have review for this one. > > For some reason I don't have cc:stable on this - could people > make a recommendation? > I will get to this in couple of days (hopefully sooner). I think Johannes was looking into this as well.