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 B9DF33385A7; Thu, 2 Jul 2026 16:32:20 +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=1783009941; cv=none; b=VbEMOYYYrp8X6ojnD/zZULyDTjhRz1eMUEWtMCFDZcqtxdgyt8mFZYGriSQVLmePtAVVsLxs0Uacj6+Og3aEgRzuYmHmvdHiTgVcg0RAwZICFMH+YjBRFURJyXpb1Pr3CkY1QICuSSS5k/9kC3QJxh2gmCbvgYTTg79xmY67vMc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783009941; c=relaxed/simple; bh=bqQ/TLV7qDXbqJELw1eAIbjlyjla+ML5r/9NUO+uKjA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=cXuT2EQJk2wmHWN8nAQuVdKLzBT7BlHSYG80iKpVZGiM+wQUJxZE/AFR1SC92CFEZvkv+AktaESwTuFRbGrqBWqUGsyqC8t/j3E8Q7tNu8XqAvsZFjz4OWC+8ehli0/wKj7XTICzFYT2lxaPILIHa+zhp8IHzheCrd6bYxlDPlM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Zl03/L7R; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Zl03/L7R" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2CD451F00A3A; Thu, 2 Jul 2026 16:32:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1783009940; bh=DJpjH9SoXbhdA906vf975aRz4iZAVBiJs0zVvsspfAE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Zl03/L7R8ltdiF8R9YHRpP5xASY4L86PSpIaULO2zmypvDO8MncwdYjiyVbJ937pU /Vh4puLR0bsV6UmgtUIKNEenslPoESD2uDTS2ufBd/6P+rCd7BOgJ9Z/AYScAV30et QN+kh209XBPGhWhv6eP05K0XelCJHUqlUjGOaC4o= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yu Zhao , syzbot+03fd9b3f71641f0ebf2d@syzkaller.appspotmail.com, Andrew Morton , Jakov Novak , Sasha Levin Subject: [PATCH 6.1 049/129] mm/mglru: skip special VMAs in lru_gen_look_around() Date: Thu, 2 Jul 2026 18:19:28 +0200 Message-ID: <20260702155113.165543024@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260702155112.163984240@linuxfoundation.org> References: <20260702155112.163984240@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yu Zhao [ Upstream commit c28ac3c7eb945fee6e20f47d576af68fdff1392a ] Special VMAs like VM_PFNMAP can contain anon pages from COW. There isn't much profit in doing lookaround on them. Besides, they can trigger the pte_special() warning in get_pte_pfn(). Skip them in lru_gen_look_around(). Link: https://lkml.kernel.org/r/20231223045647.1566043-1-yuzhao@google.com Fixes: 018ee47f1489 ("mm: multi-gen LRU: exploit locality in rmap") Signed-off-by: Yu Zhao Reported-by: syzbot+03fd9b3f71641f0ebf2d@syzkaller.appspotmail.com Closes: https://lore.kernel.org/000000000000f9ff00060d14c256@google.com/ Cc: Signed-off-by: Andrew Morton [fix conflicts with variable declarations and vma pointer usage] Signed-off-by: Jakov Novak Signed-off-by: Sasha Levin --- mm/vmscan.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 1f7a90ecc7007d..f6f8c18dc45f57 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -4622,6 +4622,7 @@ void lru_gen_look_around(struct page_vma_mapped_walk *pvmw) struct lru_gen_mm_walk *walk; int young = 0; unsigned long bitmap[BITS_TO_LONGS(MIN_LRU_BATCH)] = {}; + struct vm_area_struct *vma = pvmw->vma; struct folio *folio = pfn_folio(pvmw->pfn); struct mem_cgroup *memcg = folio_memcg(folio); struct pglist_data *pgdat = folio_pgdat(folio); @@ -4635,11 +4636,15 @@ void lru_gen_look_around(struct page_vma_mapped_walk *pvmw) if (spin_is_contended(pvmw->ptl)) return; + /* exclude special VMAs containing anon pages from COW */ + if (vma->vm_flags & VM_SPECIAL) + return; + /* avoid taking the LRU lock under the PTL when possible */ walk = current->reclaim_state ? current->reclaim_state->mm_walk : NULL; - start = max(pvmw->address & PMD_MASK, pvmw->vma->vm_start); - end = min(pvmw->address | ~PMD_MASK, pvmw->vma->vm_end - 1) + 1; + start = max(pvmw->address & PMD_MASK, vma->vm_start); + end = min(pvmw->address | ~PMD_MASK, vma->vm_end - 1) + 1; if (end - start > MIN_LRU_BATCH * PAGE_SIZE) { if (pvmw->address - start < MIN_LRU_BATCH * PAGE_SIZE / 2) @@ -4660,7 +4665,7 @@ void lru_gen_look_around(struct page_vma_mapped_walk *pvmw) for (i = 0, addr = start; addr != end; i++, addr += PAGE_SIZE) { unsigned long pfn; - pfn = get_pte_pfn(pte[i], pvmw->vma, addr); + pfn = get_pte_pfn(pte[i], vma, addr); if (pfn == -1) continue; @@ -4671,7 +4676,7 @@ void lru_gen_look_around(struct page_vma_mapped_walk *pvmw) if (!folio) continue; - if (!ptep_test_and_clear_young(pvmw->vma, addr, pte + i)) + if (!ptep_test_and_clear_young(vma, addr, pte + i)) VM_WARN_ON_ONCE(true); young++; -- 2.53.0