From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 9272F6D6E4; Mon, 8 Jan 2024 15:14:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="kO45VY8R" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EAE98C433C8; Mon, 8 Jan 2024 15:14:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1704726886; bh=orBrWnFWKBH6exYez9qDH8gLxjum2IUVYCFvoiPL9uE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kO45VY8R+vf3eeQs5LgYT2/DGXx2beWktYRWLQyFpNs/zA1mPsQ2dN062xAALKxP7 80peXt3xCiRyqMYsWZA15+P0Vang/42n82LtA2GWoITw6Vjf2WxPDEwkV26Y1ZcNtA StCrplKUT/FVfPp6XRaYgqsOqkg21B8oEijspmbI= 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 Subject: [PATCH 6.6 109/124] mm/mglru: skip special VMAs in lru_gen_look_around() Date: Mon, 8 Jan 2024 16:08:55 +0100 Message-ID: <20240108150607.977597911@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240108150602.976232871@linuxfoundation.org> References: <20240108150602.976232871@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yu Zhao commit c28ac3c7eb945fee6e20f47d576af68fdff1392a upstream. 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 Signed-off-by: Greg Kroah-Hartman --- mm/vmscan.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -4656,6 +4656,7 @@ void lru_gen_look_around(struct page_vma int young = 0; pte_t *pte = pvmw->pte; unsigned long addr = pvmw->address; + struct vm_area_struct *vma = pvmw->vma; struct folio *folio = pfn_folio(pvmw->pfn); bool can_swap = !folio_is_file_lru(folio); struct mem_cgroup *memcg = folio_memcg(folio); @@ -4670,11 +4671,15 @@ void lru_gen_look_around(struct page_vma 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(addr & PMD_MASK, pvmw->vma->vm_start); - end = min(addr | ~PMD_MASK, pvmw->vma->vm_end - 1) + 1; + start = max(addr & PMD_MASK, vma->vm_start); + end = min(addr | ~PMD_MASK, vma->vm_end - 1) + 1; if (end - start > MIN_LRU_BATCH * PAGE_SIZE) { if (addr - start < MIN_LRU_BATCH * PAGE_SIZE / 2) @@ -4699,7 +4704,7 @@ void lru_gen_look_around(struct page_vma unsigned long pfn; pte_t ptent = ptep_get(pte + i); - pfn = get_pte_pfn(ptent, pvmw->vma, addr); + pfn = get_pte_pfn(ptent, vma, addr); if (pfn == -1) continue; @@ -4710,7 +4715,7 @@ void lru_gen_look_around(struct page_vma 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++;