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 47CF642AA9 for ; Thu, 13 Mar 2025 20:41:03 +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=1741898464; cv=none; b=tnNwV6XTGMSGeBkrQjwz8c0MF/oGkF9PZQNFuCr332cEmo2B9PKvC6CoTJNR6T2eifIXm6nQ7EB85fUsGgt5fK1WCJthRecZ25UEi1lvlLPNY33QPuXQaWQtRAkrMPz3CJuWT63aVCh9RWFR5jyJhzatf14aw4vmaySMjkBSo8k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741898464; c=relaxed/simple; bh=T1OMaRsXWgjX4cU/HOFkmiapo0qdTxP4fXUYabnYQ1Q=; h=Date:To:From:Subject:Message-Id; b=bfFDRn+ECTr730V9+cvtWhtWnG9SbBGPEWxqD+oYfx70nh/v3FxssOSJIHre72tCo4zP97pEfY2wVpTwVJTUzrvb4NAVFDf3Jf3Pb1FfWYqq1rs5KbSwEkQAuiyNIWnw3C+kFSWEAkQSDVibAwpS7ksGeRyuaVtzT8pZjS4RPAQ= 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=QhOZjkKE; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="QhOZjkKE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A160EC4CEDD; Thu, 13 Mar 2025 20:41:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1741898463; bh=T1OMaRsXWgjX4cU/HOFkmiapo0qdTxP4fXUYabnYQ1Q=; h=Date:To:From:Subject:From; b=QhOZjkKE1zufSMWmAWwFTdc9aexm3CmFkxiqa5qyVbWAnKZtoy4CsK/O5oB7SSY5Q 8bU0OQaaRnk2YjaBhI0ExEV7Q7a2tqTc7Jutquo378Y3jE8C7+StIlkB3dFzMEdLUG fQi+Na1L0IaCmx7fgcYiUrcOl6sJerB5LzdzpMck= Date: Thu, 13 Mar 2025 13:41:03 -0700 To: mm-commits@vger.kernel.org,yosryahmed@google.com,ying.huang@linux.alibaba.com,willy@infradead.org,v-songbaohua@oppo.com,nphamcs@gmail.com,kaleshsingh@google.com,hughd@google.com,hannes@cmpxchg.org,chrisl@kernel.org,bhe@redhat.com,baolin.wang@linux.alibaba.com,kasong@tencent.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-swap-avoid-redundant-swap-device-pinning.patch added to mm-unstable branch Message-Id: <20250313204103.A160EC4CEDD@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm, swap: avoid redundant swap device pinning has been added to the -mm mm-unstable branch. Its filename is mm-swap-avoid-redundant-swap-device-pinning.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-swap-avoid-redundant-swap-device-pinning.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Kairui Song Subject: mm, swap: avoid redundant swap device pinning Date: Fri, 14 Mar 2025 00:59:31 +0800 Currently __read_swap_cache_async() has get/put_swap_device() calls to increase/decrease a swap device reference to prevent swapoff. While some of its callers have already held the swap device reference, e.g in do_swap_page() and shmem_swapin_folio() where __read_swap_cache_async() will finally called. Now there are only two callers not holding a swap device reference, so make them hold a reference instead. And drop the get/put_swap_device calls in __read_swap_cache_async. This should reduce the overhead for swap in during page fault slightly. Link: https://lkml.kernel.org/r/20250313165935.63303-4-ryncsn@gmail.com Signed-off-by: Kairui Song Reviewed-by: Baoquan He Cc: Baolin Wang Cc: Barry Song Cc: Chris Li Cc: "Huang, Ying" Cc: Hugh Dickins Cc: Johannes Weiner Cc: Kalesh Singh Cc: Matthew Wilcow (Oracle) Cc: Nhat Pham Cc: Yosry Ahmed Signed-off-by: Andrew Morton --- mm/swap_state.c | 14 ++++++++------ mm/zswap.c | 8 +++++++- 2 files changed, 15 insertions(+), 7 deletions(-) --- a/mm/swap_state.c~mm-swap-avoid-redundant-swap-device-pinning +++ a/mm/swap_state.c @@ -426,17 +426,13 @@ struct folio *__read_swap_cache_async(sw struct mempolicy *mpol, pgoff_t ilx, bool *new_page_allocated, bool skip_if_exists) { - struct swap_info_struct *si; + struct swap_info_struct *si = swp_swap_info(entry); struct folio *folio; struct folio *new_folio = NULL; struct folio *result = NULL; void *shadow = NULL; *new_page_allocated = false; - si = get_swap_device(entry); - if (!si) - return NULL; - for (;;) { int err; /* @@ -532,7 +528,6 @@ fail_unlock: put_swap_folio(new_folio, entry); folio_unlock(new_folio); put_and_return: - put_swap_device(si); if (!(*new_page_allocated) && new_folio) folio_put(new_folio); return result; @@ -552,11 +547,16 @@ struct folio *read_swap_cache_async(swp_ struct vm_area_struct *vma, unsigned long addr, struct swap_iocb **plug) { + struct swap_info_struct *si; bool page_allocated; struct mempolicy *mpol; pgoff_t ilx; struct folio *folio; + si = get_swap_device(entry); + if (!si) + return NULL; + mpol = get_vma_policy(vma, addr, 0, &ilx); folio = __read_swap_cache_async(entry, gfp_mask, mpol, ilx, &page_allocated, false); @@ -564,6 +564,8 @@ struct folio *read_swap_cache_async(swp_ if (page_allocated) swap_read_folio(folio, plug); + + put_swap_device(si); return folio; } --- a/mm/zswap.c~mm-swap-avoid-redundant-swap-device-pinning +++ a/mm/zswap.c @@ -1051,14 +1051,20 @@ static int zswap_writeback_entry(struct struct folio *folio; struct mempolicy *mpol; bool folio_was_allocated; + struct swap_info_struct *si; struct writeback_control wbc = { .sync_mode = WB_SYNC_NONE, }; /* try to allocate swap cache folio */ + si = get_swap_device(swpentry); + if (!si) + return -EEXIST; + mpol = get_task_policy(current); folio = __read_swap_cache_async(swpentry, GFP_KERNEL, mpol, - NO_INTERLEAVE_INDEX, &folio_was_allocated, true); + NO_INTERLEAVE_INDEX, &folio_was_allocated, true); + put_swap_device(si); if (!folio) return -ENOMEM; _ Patches currently in -mm which might be from kasong@tencent.com are mm-swap-avoid-reclaiming-irrelevant-swap-cache.patch mm-swap-drop-the-flag-ttrs_direct.patch mm-swap-avoid-redundant-swap-device-pinning.patch mm-swap-dont-update-the-counter-up-front.patch mm-swap-use-percpu-cluster-as-allocation-fast-path.patch mm-swap-remove-swap-slot-cache.patch mm-swap-simplify-folio-swap-allocation.patch