From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F1C2F34041B; Wed, 9 Sep 2026 06:28:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788935329; cv=none; b=jI3HBgqRVYRz4N715f18JI0ihxqBrMajnH+6MUxOOteX51ryejfPMkrbydIXHDnP1cRRXKjtD93QaRcNW94bj4WYXpe/2n2Pgo2yKdqoqARJQcBfeYXL5LftqnpWUh+5aZkPf//i6h15aggt1p+WtvJD2OaXCsfj/tXWhuogJho= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788935329; c=relaxed/simple; bh=/YBVqqCwlG/Y4qiqYDB9YF4ISlUJYzsCVg2EbmPnp2g=; h=Date:To:From:Subject:Message-Id; b=jmJOTXEYJodZqHdk4qTLpNrVlZhNhoX4quaOubYsVdZb3HVbrk8rP82W88QJBo5oPhVWkm+Udj4QP6YTmfvrP+9NEIRiyU7vFqXuSua1VRmNRfZGsW/no9/sCeR9i1Obc/tD/rC5rMWkO61ZSE69mGCFeHWWkvVIyVCZNQbgnU0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=gfpVwsnb; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="gfpVwsnb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C460A1F00A3D; Wed, 9 Sep 2026 06:28:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1788935327; bh=TQ7whNqDQHLlkHRvY/G7kN+8iaXJTi9neRVI+YvtObA=; h=Date:To:From:Subject; b=gfpVwsnb4klgy37b8AH+qL64ETgO6ftY2+YRlNtBcA76jfgPImlQSSdLzMZb9rH52 Bq/3vdZwR1zSYXh2sDfvMVI14KsQ/bIFBr0JuJQEgDPdTKTEPFHwez9MWPuzMSEnUM q/rJSRf1cF6Y8xFY+67b27pBoKWiNzFiUqFZw6j0= Date: Tue, 08 Sep 2026 23:28:47 -0700 To: mm-commits@vger.kernel.org,usama.arif@linux.dev,stable@vger.kernel.org,shakeel.butt@linux.dev,roman.gushchin@linux.dev,muchun.song@linux.dev,kasong@tencent.com,hannes@cmpxchg.org,david@fromorbit.com,jiayuan.chen@linux.dev,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-hotfixes-stable] mm-shrinker-fix-bogus-set_shrinker_bit-with-cgroupmemory=nokmem.patch removed from -mm tree Message-Id: <20260909062847.C460A1F00A3D@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm/shrinker: fix bogus set_shrinker_bit() with cgroup.memory=nokmem has been removed from the -mm tree. Its filename was mm-shrinker-fix-bogus-set_shrinker_bit-with-cgroupmemory=nokmem.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Jiayuan Chen Subject: mm/shrinker: fix bogus set_shrinker_bit() with cgroup.memory=nokmem Date: Wed, 2 Sep 2026 15:37:59 +0800 With cgroup.memory=nokmem, shrinker_memcg_alloc() bails out early and never allocates an id, so shrinker->id keeps the 0 it got from the kzalloc() in shrinker_alloc(). __list_lru_init() then copies that 0 into lru->shrinker_id, where it looks like a valid bit index. Nothing calls expand_shrinker_info() on nokmem either, so shrinker_nr_max stays 0 and every memcg ends up with an empty map (map_nr_max == 0). deferred_split_folio() hands a real memcg to __list_lru_add() regardless of whether the lru is memcg aware, so the first THP queued in a cgroup does set_shrinker_bit(memcg, nid, 0) and trips the bounds check: WARNING: mm/shrinker.c:212 at set_shrinker_bit+0x7d/0x90, CPU#126 Call Trace: deferred_split_folio+0x18c/0x220 map_anon_folio_pmd_nopf+0xdd/0x130 map_anon_folio_pmd_pf+0x14/0xb0 do_huge_pmd_anonymous_page+0x1a1/0x620 __handle_mm_fault+0xea9/0x10d0 handle_mm_fault+0xe5/0x320 do_user_addr_fault+0x1cc/0x870 exc_page_fault+0x81/0x1b0 asm_exc_page_fault+0x27/0x30 Harmless, the WARN_ON_ONCE() is what keeps the out of bounds unit[] read from happening, but the id should not look valid in the first place. Clear it before returning. Two other spots could paper over this: drop the id in __list_lru_init() when nokmem turns memcg_aware off, or make deferred_split_folio() pass NULL like list_lru_add_obj() does. Both leave shrinker->id lying around for the next caller, so fix it where the id is handed out. Link: https://lore.kernel.org/20260902073800.305481-1-jiayuan.chen@linux.dev Fixes: fafaeceb89a5 ("mm: switch deferred split shrinker to list_lru") Signed-off-by: Jiayuan Chen Acked-by: Shakeel Butt Cc: Usama Arif Cc: Dave Chinner Cc: Johannes Weiner Cc: Kairui Song Cc: Muchun Song Cc: Roman Gushchin Cc: Signed-off-by: Andrew Morton --- mm/shrinker.c | 2 ++ 1 file changed, 2 insertions(+) --- a/mm/shrinker.c~mm-shrinker-fix-bogus-set_shrinker_bit-with-cgroupmemory=nokmem +++ a/mm/shrinker.c @@ -227,6 +227,8 @@ static int shrinker_memcg_alloc(struct s { int id; + shrinker->id = -1; + if (mem_cgroup_disabled()) return -ENOSYS; if (mem_cgroup_kmem_disabled() && !(shrinker->flags & SHRINKER_NONSLAB)) _ Patches currently in -mm which might be from jiayuan.chen@linux.dev are mm-memcontrol-fix-data-race-on-reading-jiffies_64.patch