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Sat, 05 Sep 2026 03:43:18 +0800 (CST) X-QQ-SSF: 0000000000000000000000000000000 X-QQ-GoodBg: 1 X-BIZMAIL-ID: 861377282768174038 EX-QQ-RecipientCnt: 15 From: Wentao Guan To: qinyuntan@linux.alibaba.com Cc: akpm@linux-foundation.org, baolin.wang@linux.alibaba.com, david@fromorbit.com, david@kernel.org, hannes@cmpxchg.org, lance.yang@linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mkoutny@suse.com, muchun.song@linux.dev, qi.zheng@linux.dev, roman.gushchin@linux.dev, xlpang@linux.alibaba.com, Wentao Guan Subject: Re: [PATCH] mm/list_lru: don't copy stale shrinker id from non-memcg-aware shrinkers Date: Sat, 5 Sep 2026 03:43:15 +0800 Message-Id: <20260904194315.9954-1-guanwentao@uniontech.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20260901115104.2944996-1-qinyuntan@linux.alibaba.com> References: <20260901115104.2944996-1-qinyuntan@linux.alibaba.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-QQ-SENDSIZE: 520 Feedback-ID: zesmtpgz:uniontech.com:qybglogicsvrgz:qybglogicsvrgz3a-0 X-QQ-XMAILINFO: OSNvDVUIgTHKtshHkV92EO0D5G0J3Gtov2NKa7SqgCGjuhy7MI1WrrWZ 1IVZAEZa0vxo4w5gG8/jWtVhovjtBjJRQsQWr8QDqt9qlKXxixGcx+h/y48tzvJWg9Oor3Z Zo8RBO2w2l5NkEO/CZnnp4+z03R7zyZHvvaV+o2LBslplyZF1Y5Kr95Gslid6a3zPjb711y M3/7kWzZvPmTpJNxfv0fCuG5HVkpH2TZ6Cjgr4y1LrNNQ+krHIvvdItCcm9ba+jTHqLFECD F/pWDOnIxW9WQmBxVWhsdUMXryfmMgAstGHpnEqcqKTT7VckQYUs5FKPfGsGVtKFl6L1W0u OP/AsBlasLbD2j84ejzDWZt5pgszzZ+GEJJzYeLPLTUsUReHpvr1Nt2OL1kfgNXkUTHPhHR wfJH9HGJVxeaSR6zBnV5/4/v3+1etgCKkEfg0KtGjr6KOX8+r5oD7+Ll/kNK/O1KHu8tbT/ AUX7APS1tqQfDNeQpDKEJghAe8WEtLvyBIdxKRqEKzvfe1M3vJKs9UOmPmVlUzWWVmM3oiF c1mriYH3KoNzS788mtxFo+T6lWqh45kZriQiqQJRTQUdpHsIvq81WqeLKUJ5GdwQXdMdvbd XBkrcuXYDmRe673VJOCUVx+eV4oQnDnDFliu9bvexTpMrO1RlghTIdN8kU6/Jm4IGACaCRn J9s1vWZS6l6JaE7XEBK1oo3V0aNrtXEKRpuNe6XAybUCdRAKsR82APPOYplhdR9AkQLwM2A eVQstSlmYfnGW+eueOC8N5cip2h/WU9QqV2XY0nrtOSIjr3vOUDF+knTCOEq+W8G1CmKWDB F7a8jmrb8N6ACItn8jDut9r71LjD3UD+8nkstJjiUlaaqlYzwBmhdUJEkHb0N2mz0kc/uMu /WGiBr9cNeuW4fkimffudUzs8miQPFszozoFGsKZi8MGuoOioeCINJDQ0NRMGJa8pFh97wF 58xkAAeveF3QYV82Ib1tGysk3SUIOcgpby/4yjBrSOMXNWR9eIvyuElVQSUZM0ce7+KiYbA x2tSFVaV/oo5YWA1raNguSSwzhlU12wzSnK+OpvZakiBuG6tYNKwhqCmprasOgAxNior/Pw 7yOahdIAejXIquKJtrYbpXqqBw0PXV30Q== X-QQ-XMRINFO: MPJ6Tf5t3I/ylTmHUqvI8+Wpn+Gzalws3A== X-QQ-RECHKSPAM: 0 X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: BE49440007 X-Stat-Signature: bkhw4bk8fj1y1szpz7o1y88q76anb45g X-Rspam-User: X-HE-Tag: 1788551060-173345 X-HE-Meta: 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 ob+HCO9i 7ONYHG7z3sDBZ+8lieAgdYi27fQcsVimVyP/wcypVUaX8WGeLywHGDM03z6/NMeu72KkMR/9Eo3slssrhd/JhETO/yuABJsMsJBe3SVPm6xb+BMpq8l9Uh7zhPnMHZMYOBoo7c08wON+3RbNK+ps8tl4EPDZD/G5FaLBW4wIB3qiYKSjAF8m1J7GLtIhJH6lSU7jUp28khrhYzrzZxQ/wEdXFasc4MTXItZZC5+e6kMsI8aqz2HIMNht7MJ3x5hzglKkwUo58NG3dUmRfXqAI+f+mFBfgp7QjhkPyp1TMxiHWaWpK3pO9GqqHQPylSVBlwyrsQh/oTgkbrDkWGBYaOJhoGRrPH2yK1cecMU1AFXx+oFSJj7rsuAKM7NZB9Bj3XayI9PAIMVrGA4XOdipphuymyfg/kUZgiQDWayNw2GS/xpfX+PpfrrU1YA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > On Sep 1, 2026, at 19:51, Qinyun Tan wrote: > > With cgroup.memory=nokmem, shrinker_memcg_alloc() fails with -ENOSYS > for shrinkers without SHRINKER_NONSLAB, and shrinker_alloc() falls > back to a non-memcg-aware shrinker. On this fallback path, > shrinker->id is never assigned and keeps 0 from kzalloc(), which is a > valid id belonging to whichever memcg-aware shrinker registers first. > > __list_lru_init() copies shrinker->id unconditionally, so every > list_lru backed by such a fallback shrinker (thp-deferred_split, > zswap-shrinker, workingset shadow nodes, superblock lrus, ...) ends > up with lru->shrinker_id == 0 instead of -1. > > Under nokmem the list_lru collapses to the shared per-node lists, but > __list_lru_add() still calls set_shrinker_bit() against the memcg of > the added object. Most list_lru users are unaffected because their > objects resolve to a NULL memcg without kmem accounting, but the THP > deferred split queue holds user folios, which are charged regardless > of nokmem. Since no memcg-aware shrinker can register under nokmem, > shrinker_nr_max stays 0 and every memcg's shrinker_info has > map_nr_max == 0, so the first folio added by khugepaged triggers on > every boot: > > WARNING: mm/shrinker.c:212 at set_shrinker_bit+0x99/0xa0 > > On systems where a SHRINKER_NONSLAB shrinker (btrfs, xfs) did register > and expand the maps, there is no warning; instead bit 0 is set > spuriously for an unrelated shrinker. > > shrinker->id is only meaningful while SHRINKER_MEMCG_AWARE is set, > and all readers inside mm/shrinker.c already check the flag before > using the id. Make __list_lru_init() do the same and fall back to -1, > so set_shrinker_bit() is never reached with a bogus id. The stale > shrinker->id itself is left as is; cleaning that up is a separate > topic. > > Fixes: 03375203e1da8 ("mm: do not allocate shrinker info with cgroup.memory=nokmem") > Signed-off-by: Qinyun Tan Tested-by: Wentao Guan The patch solved my problem in link: https://lore.kernel.org/linux-mm/20260904190028.21542-1-guanwentao@uniontech.com/ Thanks Wentao Guan