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 926CA54BD5 for ; Mon, 26 Feb 2024 10:30:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708943422; cv=none; b=V9KLnHXEwL1OYP6KEkprDWiF+1h8vm978mj0plTkBWWD8dSOtftKhE06Nyf2KfdOkVdGzMOPEUnDdFbmPcZCTvpkyBIHgnhPauJUMGxTbRkEHMG/xjchShw3NfeI6MirWnG+/BjE8J+e4dB9MChDqiqPCaslUkrbrU3UQwOrQ9A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708943422; c=relaxed/simple; bh=5jAGusCehz6AZ90YCA6X/uJB5l873iHkO78B7R5DguA=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=NXI+qITFcxUfyIZV4a9wfFHkxvWR8L4Lq5tbSWe2UF6r5xC+/WUjXUlMcgXARPl6Z9/gvArA8xjcEE6WYmrIjsOGxO/CUYl+eqEkYL6f6Ususs3CSHYR1cgLvn7yDcBLX2E+eZVmCvY/XWfzplbi6WEm5quzaYlu5yWkE4+nCDM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=UQ22uyJJ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="UQ22uyJJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D4C02C433C7; Mon, 26 Feb 2024 10:30:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1708943422; bh=5jAGusCehz6AZ90YCA6X/uJB5l873iHkO78B7R5DguA=; h=Subject:To:Cc:From:Date:From; b=UQ22uyJJJTRI8otr8aCfiVD5gU2D6mfFXwayg3EbwhYIGK1SungPF7UyICT7XKNQo Gz55F8WbvFZMwQwYk8TgVBV2Cb57jFYr7DzSAfiOUXnIDUgN/OxIm2Po353SNxtgF0 DTXRScy8vL7iukO0DN/0EV+ru2qwk2Nh0Sx74GSA= Subject: FAILED: patch "[PATCH] mm: zswap: fix missing folio cleanup in writeback race path" failed to apply to 6.6-stable tree To: yosryahmed@google.com,akpm@linux-foundation.org,cerasuolodomenico@gmail.com,hannes@cmpxchg.org,nphamcs@gmail.com,stable@vger.kernel.org,zhouchengming@bytedance.com Cc: From: Date: Mon, 26 Feb 2024 11:30:11 +0100 Message-ID: <2024022611-tropics-deferred-2483@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x e3b63e966cac0bf78aaa1efede1827a252815a1d # git commit -s git send-email --to '' --in-reply-to '2024022611-tropics-deferred-2483@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^.. Possible dependencies: e3b63e966cac ("mm: zswap: fix missing folio cleanup in writeback race path") 96c7b0b42239 ("mm: return the folio from __read_swap_cache_async()") e947ba0bbf47 ("mm/zswap: cleanup zswap_writeback_entry()") 32acba4c0483 ("mm/zswap: refactor out __zswap_load()") c75f5c1e0f1d ("mm/zswap: reuse dstmem when decompress") b5ba474f3f51 ("zswap: shrink zswap pool based on memory pressure") a65b0e7607cc ("zswap: make shrinking memcg-aware") ddc1a5cbc05d ("mempolicy: alloc_pages_mpol() for NUMA policy without vma") 23e4883248f0 ("mm: add page_rmappable_folio() wrapper") c36f6e6dff4d ("mempolicy trivia: slightly more consistent naming") 7f1ee4e20708 ("mempolicy trivia: delete those ancient pr_debug()s") 1cb5d11a370f ("mempolicy: fix migrate_pages(2) syscall return nr_failed") 3657fdc2451a ("mm: move vma_policy() and anon_vma_name() decls to mm_types.h") 3022fd7af960 ("shmem: _add_to_page_cache() before shmem_inode_acct_blocks()") 054a9f7ccd0a ("shmem: move memcg charge out of shmem_add_to_page_cache()") 4199f51a7eb2 ("shmem: shmem_acct_blocks() and shmem_inode_acct_blocks()") e3e1a5067fd2 ("shmem: remove vma arg from shmem_get_folio_gfp()") 75c70128a673 ("mm: mempolicy: make mpol_misplaced() to take a folio") cda6d93672ac ("mm: memory: make numa_migrate_prep() to take a folio") 6695cf68b15c ("mm: memory: use a folio in do_numa_page()") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From e3b63e966cac0bf78aaa1efede1827a252815a1d Mon Sep 17 00:00:00 2001 From: Yosry Ahmed Date: Thu, 25 Jan 2024 08:51:27 +0000 Subject: [PATCH] mm: zswap: fix missing folio cleanup in writeback race path In zswap_writeback_entry(), after we get a folio from __read_swap_cache_async(), we grab the tree lock again to check that the swap entry was not invalidated and recycled. If it was, we delete the folio we just added to the swap cache and exit. However, __read_swap_cache_async() returns the folio locked when it is newly allocated, which is always true for this path, and the folio is ref'd. Make sure to unlock and put the folio before returning. This was discovered by code inspection, probably because this path handles a race condition that should not happen often, and the bug would not crash the system, it will only strand the folio indefinitely. Link: https://lkml.kernel.org/r/20240125085127.1327013-1-yosryahmed@google.com Fixes: 04fc7816089c ("mm: fix zswap writeback race condition") Signed-off-by: Yosry Ahmed Reviewed-by: Chengming Zhou Acked-by: Johannes Weiner Reviewed-by: Nhat Pham Cc: Domenico Cerasuolo Cc: Signed-off-by: Andrew Morton diff --git a/mm/zswap.c b/mm/zswap.c index 350dd2fc8159..d2423247acfd 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -1440,6 +1440,8 @@ static int zswap_writeback_entry(struct zswap_entry *entry, if (zswap_rb_search(&tree->rbroot, swp_offset(entry->swpentry)) != entry) { spin_unlock(&tree->lock); delete_from_swap_cache(folio); + folio_unlock(folio); + folio_put(folio); return -ENOMEM; } spin_unlock(&tree->lock);