From patchwork Fri Mar 31 07:08:16 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yosry Ahmed X-Patchwork-Id: 13195312 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 815EAC77B6E for ; Fri, 31 Mar 2023 07:08:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230415AbjCaHI0 (ORCPT ); Fri, 31 Mar 2023 03:08:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58470 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230390AbjCaHIZ (ORCPT ); Fri, 31 Mar 2023 03:08:25 -0400 Received: from mail-pl1-x649.google.com (mail-pl1-x649.google.com [IPv6:2607:f8b0:4864:20::649]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0853AC676 for ; Fri, 31 Mar 2023 00:08:24 -0700 (PDT) Received: by mail-pl1-x649.google.com with SMTP id f6-20020a170902ce8600b001a25ae310a9so6886206plg.10 for ; Fri, 31 Mar 2023 00:08:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1680246503; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=B2pWBeS3GCf3oNfr31dlSqb/2UGMYxzBqyAxEtHKHDE=; b=k4NyjagiGkCklbJVsqIMtonbdCMcTupGTS8hoHaC0gv8FOGuM+Bs5S57llv7e0EaSv Cdr8aYY+xrBbCtFlM6wcVGLHr43sIVgLRjo6N9VGVd6RPJWbRRFixWbs+ilYQFqKNFaX XmIjhQjyQd9NZkc3tv9rRK0BApt1ddgQG5Hmi7auJiptlkO709XlGaRHtR6d3pQ9Avj3 N34PvmS9EWNDok32raE4oK5g8hggDeU3zDAViHIjtdEdByWnmMFFSaEjcfkCBkO01CnD 9fsOaBbQNmSszl6BuqVSwa5jOVOxj6sT1Ok05l7fpvj5jCSBxdjsIIURvPSg0lRWYZMb t+xQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680246503; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=B2pWBeS3GCf3oNfr31dlSqb/2UGMYxzBqyAxEtHKHDE=; b=jN0CDg1IZyGD6Aq2o2UmfbQesVm5WqUTvwo0DTCzmednAtl2CHUt+919qEtIfgrpv+ jMzWtS2Qhi20lNDovao2w+tWGyFCSd9q8GBkV7peTYZgOMgieZYKnvly1j4U45RokVI6 uVV0J3eIefIKh6sh/Fm1iDr76I5elHXs12AZIGbS4fY1+y5OYPeIYY/GZq6+ogykpezM oILi/kVZAF5987WEGk/ENBDTdZDlZ6hcyZPumjSmVKNn7cpaMxvxwACKzHoR2n7OW1Vm BSg77Q5VDnf53BzQQg2emeCjUzKP4m2amkrpA3tTySCykuMyfiSqevLxr0rWzP5FK2M+ 5Mig== X-Gm-Message-State: AAQBX9em/fBHtRc4usjnsMdYCSYSCSJpoKIutBhB7jCwY2yDJr3NJwL3 EEbz01i814tfKPUnf49WTl9Dzdi+IhNe1TsU X-Google-Smtp-Source: AKy350bRvjgd15ALJuao0xdVFVls0BdarK49AoD9W3kOxaJ3kd852in4QhALpf6ZkL2aYK5+VCe3mI8yGkJLtLkv X-Received: from yosry.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:2327]) (user=yosryahmed job=sendgmr) by 2002:a17:902:9b87:b0:1a2:1c7:1c1b with SMTP id y7-20020a1709029b8700b001a201c71c1bmr8812952plp.5.1680246503444; Fri, 31 Mar 2023 00:08:23 -0700 (PDT) Date: Fri, 31 Mar 2023 07:08:16 +0000 In-Reply-To: <20230331070818.2792558-1-yosryahmed@google.com> Mime-Version: 1.0 References: <20230331070818.2792558-1-yosryahmed@google.com> X-Mailer: git-send-email 2.40.0.348.gf938b09366-goog Message-ID: <20230331070818.2792558-2-yosryahmed@google.com> Subject: [PATCH v3 1/3] mm: vmscan: move set_task_reclaim_state() after cgroup_reclaim() From: Yosry Ahmed To: Andrew Morton , Alexander Viro , "Darrick J. Wong" , Christoph Lameter , David Rientjes , Joonsoo Kim , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, "Matthew Wilcox (Oracle)" , Miaohe Lin , David Hildenbrand , Johannes Weiner , Peter Xu , NeilBrown , Shakeel Butt , Michal Hocko , Yu Zhao , Dave Chinner Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org, Yosry Ahmed Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org set_task_reclaim_state() is currently defined in mm/vmscan.c above an #ifdef CONFIG_MEMCG block where cgroup_reclaim() is defined. We are about to add some more helpers that operate on reclaim_state, and will need to use cgroup_reclaim(). Move set_task_reclaim_state() after the #ifdef CONFIG_MEMCG block containing the definition of cgroup_reclaim() to keep helpers operating on reclaim_state together. Signed-off-by: Yosry Ahmed --- mm/vmscan.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 9c1c5e8b24b8f..fef7d1c0f82b2 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -188,18 +188,6 @@ struct scan_control { */ int vm_swappiness = 60; -static void set_task_reclaim_state(struct task_struct *task, - struct reclaim_state *rs) -{ - /* Check for an overwrite */ - WARN_ON_ONCE(rs && task->reclaim_state); - - /* Check for the nulling of an already-nulled member */ - WARN_ON_ONCE(!rs && !task->reclaim_state); - - task->reclaim_state = rs; -} - LIST_HEAD(shrinker_list); DECLARE_RWSEM(shrinker_rwsem); @@ -511,6 +499,18 @@ static bool writeback_throttling_sane(struct scan_control *sc) } #endif +static void set_task_reclaim_state(struct task_struct *task, + struct reclaim_state *rs) +{ + /* Check for an overwrite */ + WARN_ON_ONCE(rs && task->reclaim_state); + + /* Check for the nulling of an already-nulled member */ + WARN_ON_ONCE(!rs && !task->reclaim_state); + + task->reclaim_state = rs; +} + static long xchg_nr_deferred(struct shrinker *shrinker, struct shrink_control *sc) { From patchwork Fri Mar 31 07:08:17 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yosry Ahmed X-Patchwork-Id: 13195313 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5A875C76196 for ; Fri, 31 Mar 2023 07:08:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230429AbjCaHIo (ORCPT ); Fri, 31 Mar 2023 03:08:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58686 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230431AbjCaHI3 (ORCPT ); Fri, 31 Mar 2023 03:08:29 -0400 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 275981115F for ; Fri, 31 Mar 2023 00:08:26 -0700 (PDT) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-546422bd3ceso35679617b3.21 for ; Fri, 31 Mar 2023 00:08:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1680246505; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=EVZwB8yF2h7dd4fmRqNpsJbSVI4UBUJ0tNYnQMZkjKk=; b=Qvh1jjxMNNvin3fUDDF8N+zZ8dqqA9V78pIPC9J4eiet7qDkXN9KmmYYGJUPeJYaHs MKLH6pNXsD05xRQcVpFEEfGwpCvmj99CxoROc64tCepIXuXgVcLXkcyqrZDmsVbfc/un 7sfS8XWr9MjceXgEsPIOeI1S+8cmvT09eKc373lVeEeUsWXJ702WCHk+gyMUxa0d13mH DpL6cgiWqKJVgtXn1VwPDG4acoSGVNKXwkCh7EQWTotbaEfnfpggZPHjxNETB9GJ4f25 tJPNvYQSCiMrvuPAqeNaMz0m/mU2f6x/6ZvXVSUmCM0sHbOErJEOuuXNLHg8qMP+5e4a yxRA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680246505; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=EVZwB8yF2h7dd4fmRqNpsJbSVI4UBUJ0tNYnQMZkjKk=; b=LIcd9AtVnLKDSv/Nw2RW0RGXMIouWKdiZZ82PBn2fdRhm4jO7NUDYp7QyMIEfsAHR5 JHhD8asNsNtNAaD5e+oGH9rVf7DEguRtmppH8AqtOJXB9H9sW+kf/AD7FqXFhn/vYXHc BtK/7/LtKaUC6agT2ItwCGTlQBDcYXowSHU5ewiAyMd5go8HzhnAgba+ScDQ9BrMz7HA ppkVH/4nHm85mARflJ0KjrnTE2sl3/Y2OgAFZycbUegnByXq3zpYZtb/aQ8OQKGna++T pQN63G0DKt1ci/8qWvklhpv8Jn5F0SCgLhrbDu1+zOW+hjHz+8mnKgbBCzTl4QSeiCc/ dBnw== X-Gm-Message-State: AAQBX9ed+FKHoaLPmkOm90pd65EoA1ZqXuAWGIcGJW4lTKqi+JHnt11e J8M6i5Y3ayaml7dOgNpIshoVKYgeEipaHZ7J X-Google-Smtp-Source: AKy350acSxAChLfmqKO9826eoY8acajFCu3SAUOtEMLxv1trgvamSCxttKg1ftNmirCAT6DUp5LYAYXEe4TbOfrd X-Received: from yosry.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:2327]) (user=yosryahmed job=sendgmr) by 2002:a05:6902:188f:b0:b78:bced:2e3d with SMTP id cj15-20020a056902188f00b00b78bced2e3dmr15320634ybb.3.1680246505338; Fri, 31 Mar 2023 00:08:25 -0700 (PDT) Date: Fri, 31 Mar 2023 07:08:17 +0000 In-Reply-To: <20230331070818.2792558-1-yosryahmed@google.com> Mime-Version: 1.0 References: <20230331070818.2792558-1-yosryahmed@google.com> X-Mailer: git-send-email 2.40.0.348.gf938b09366-goog Message-ID: <20230331070818.2792558-3-yosryahmed@google.com> Subject: [PATCH v3 2/3] mm: vmscan: refactor updating reclaimed pages in reclaim_state From: Yosry Ahmed To: Andrew Morton , Alexander Viro , "Darrick J. Wong" , Christoph Lameter , David Rientjes , Joonsoo Kim , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, "Matthew Wilcox (Oracle)" , Miaohe Lin , David Hildenbrand , Johannes Weiner , Peter Xu , NeilBrown , Shakeel Butt , Michal Hocko , Yu Zhao , Dave Chinner Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org, Yosry Ahmed Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org During reclaim, we keep track of pages reclaimed from other means than LRU-based reclaim through scan_control->reclaim_state->reclaimed_slab, which we stash a pointer to in current task_struct. However, we keep track of more than just reclaimed slab pages through this. We also use it for clean file pages dropped through pruned inodes, and xfs buffer pages freed. Rename reclaimed_slab to reclaimed, and add a helper function that wraps updating it through current, so that future changes to this logic are contained within mm/vmscan.c. Signed-off-by: Yosry Ahmed --- fs/inode.c | 3 +-- fs/xfs/xfs_buf.c | 3 +-- include/linux/swap.h | 5 ++++- mm/slab.c | 3 +-- mm/slob.c | 6 ++---- mm/slub.c | 5 ++--- mm/vmscan.c | 36 ++++++++++++++++++++++++++++++------ 7 files changed, 41 insertions(+), 20 deletions(-) diff --git a/fs/inode.c b/fs/inode.c index 4558dc2f13557..e60fcc41faf17 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -864,8 +864,7 @@ static enum lru_status inode_lru_isolate(struct list_head *item, __count_vm_events(KSWAPD_INODESTEAL, reap); else __count_vm_events(PGINODESTEAL, reap); - if (current->reclaim_state) - current->reclaim_state->reclaimed_slab += reap; + mm_account_reclaimed_pages(reap); } iput(inode); spin_lock(lru_lock); diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c index 54c774af6e1c6..15d1e5a7c2d34 100644 --- a/fs/xfs/xfs_buf.c +++ b/fs/xfs/xfs_buf.c @@ -286,8 +286,7 @@ xfs_buf_free_pages( if (bp->b_pages[i]) __free_page(bp->b_pages[i]); } - if (current->reclaim_state) - current->reclaim_state->reclaimed_slab += bp->b_page_count; + mm_account_reclaimed_pages(bp->b_page_count); if (bp->b_pages != bp->b_page_array) kmem_free(bp->b_pages); diff --git a/include/linux/swap.h b/include/linux/swap.h index 209a425739a9f..589ea2731931f 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -153,13 +153,16 @@ union swap_header { * memory reclaim */ struct reclaim_state { - unsigned long reclaimed_slab; + /* pages reclaimed outside of LRU-based reclaim */ + unsigned long reclaimed; #ifdef CONFIG_LRU_GEN /* per-thread mm walk data */ struct lru_gen_mm_walk *mm_walk; #endif }; +void mm_account_reclaimed_pages(unsigned long pages); + #ifdef __KERNEL__ struct address_space; diff --git a/mm/slab.c b/mm/slab.c index dabc2a671fc6f..64bf1de817b24 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -1392,8 +1392,7 @@ static void kmem_freepages(struct kmem_cache *cachep, struct slab *slab) smp_wmb(); __folio_clear_slab(folio); - if (current->reclaim_state) - current->reclaim_state->reclaimed_slab += 1 << order; + mm_account_reclaimed_pages(1 << order); unaccount_slab(slab, order, cachep); __free_pages(&folio->page, order); } diff --git a/mm/slob.c b/mm/slob.c index fe567fcfa3a39..79cc8680c973c 100644 --- a/mm/slob.c +++ b/mm/slob.c @@ -61,7 +61,7 @@ #include #include -#include /* struct reclaim_state */ +#include /* mm_account_reclaimed_pages() */ #include #include #include @@ -211,9 +211,7 @@ static void slob_free_pages(void *b, int order) { struct page *sp = virt_to_page(b); - if (current->reclaim_state) - current->reclaim_state->reclaimed_slab += 1 << order; - + mm_account_reclaimed_pages(1 << order); mod_node_page_state(page_pgdat(sp), NR_SLAB_UNRECLAIMABLE_B, -(PAGE_SIZE << order)); __free_pages(sp, order); diff --git a/mm/slub.c b/mm/slub.c index 39327e98fce34..7aa30eef82350 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -11,7 +11,7 @@ */ #include -#include /* struct reclaim_state */ +#include /* mm_account_reclaimed_pages() */ #include #include #include @@ -2063,8 +2063,7 @@ static void __free_slab(struct kmem_cache *s, struct slab *slab) /* Make the mapping reset visible before clearing the flag */ smp_wmb(); __folio_clear_slab(folio); - if (current->reclaim_state) - current->reclaim_state->reclaimed_slab += pages; + mm_account_reclaimed_pages(pages); unaccount_slab(slab, order, s); __free_pages(&folio->page, order); } diff --git a/mm/vmscan.c b/mm/vmscan.c index fef7d1c0f82b2..a3e38851b34ac 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -511,6 +511,34 @@ static void set_task_reclaim_state(struct task_struct *task, task->reclaim_state = rs; } +/* + * mm_account_reclaimed_pages(): account reclaimed pages outside of LRU-based + * reclaim + * @pages: number of pages reclaimed + * + * If the current process is undergoing a reclaim operation, increment the + * number of reclaimed pages by @pages. + */ +void mm_account_reclaimed_pages(unsigned long pages) +{ + if (current->reclaim_state) + current->reclaim_state->reclaimed += pages; +} +EXPORT_SYMBOL(mm_account_reclaimed_pages); + +/* + * flush_reclaim_state(): add pages reclaimed outside of LRU-based reclaim to + * scan_control->nr_reclaimed. + */ +static void flush_reclaim_state(struct scan_control *sc, + struct reclaim_state *rs) +{ + if (rs) { + sc->nr_reclaimed += rs->reclaimed; + rs->reclaimed = 0; + } +} + static long xchg_nr_deferred(struct shrinker *shrinker, struct shrink_control *sc) { @@ -5346,8 +5374,7 @@ static int shrink_one(struct lruvec *lruvec, struct scan_control *sc) vmpressure(sc->gfp_mask, memcg, false, sc->nr_scanned - scanned, sc->nr_reclaimed - reclaimed); - sc->nr_reclaimed += current->reclaim_state->reclaimed_slab; - current->reclaim_state->reclaimed_slab = 0; + flush_reclaim_state(sc, current->reclaim_state); return success ? MEMCG_LRU_YOUNG : 0; } @@ -6472,10 +6499,7 @@ static void shrink_node(pg_data_t *pgdat, struct scan_control *sc) shrink_node_memcgs(pgdat, sc); - if (reclaim_state) { - sc->nr_reclaimed += reclaim_state->reclaimed_slab; - reclaim_state->reclaimed_slab = 0; - } + flush_reclaim_state(sc, reclaim_state); /* Record the subtree's reclaim efficiency */ if (!sc->proactive) From patchwork Fri Mar 31 07:08:18 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yosry Ahmed X-Patchwork-Id: 13195314 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1929BC76196 for ; Fri, 31 Mar 2023 07:08:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230515AbjCaHIr (ORCPT ); Fri, 31 Mar 2023 03:08:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59228 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230409AbjCaHIm (ORCPT ); Fri, 31 Mar 2023 03:08:42 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 92EFC1A446 for ; Fri, 31 Mar 2023 00:08:27 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id z4-20020a25bb04000000b00b392ae70300so21364371ybg.21 for ; Fri, 31 Mar 2023 00:08:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1680246507; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=h76ftpfDeW349+865+C5AwRuwTE+LoTxu1YkhFCOpyA=; b=I416KE3jHWRA3QMCGUkW1ivXoY9bfwY9Wzs6ajryoP118g2lYRPUBdBs95KIolJuD5 Ethf/48kB/t99e0lZyDxt6Gzswbs6SgDsOW6Io3pxcCrt46SeVq6PdqDGwpRXRm4mIIO 6/7VlzMrDBNDNFPKTqzatAKxYD7Ykdp+wnADaTixMb98ZnvPZpzngRlNsTbR1eAqMGin OVVTVCUinbAA7DzoMhdK0NIZtCVKH1xuFjJniN2MkWrVvFG9yuSRV9r8Ey4Yt6n+qENf XWcPXE7St5/tC16GieQD7BtKre3OtF+VNgjQao02pAU8vmXwS+dEsHk1Tc7dr9q0a6L7 3Wbw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680246507; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=h76ftpfDeW349+865+C5AwRuwTE+LoTxu1YkhFCOpyA=; b=QQQX6oDZAzbwH36xUhP4hm4nRUVDbnlm0MQWUGawEXjY2KQHzRP9HMi4vI5CYoOmjZ kpoOVUT8llXHWkSg9XAfgMzT418NtNFfW+Z5nbqIasDF+bWJimunqZ5GpuZaM68/KhmJ iXVc7wRYcUn4Ydcgc1xca5v2TsbbRgPGwCWB4CKj7tVbWfgWIZJjtNPOk8OCcbg0Zw9R UK2zdeXI7C5sBsHcgx08toXmg2zqirh3BmBFQotPWg8ySdvQrCmQON3g0PO0JrVTcxoR WrRq3emgUrEAkSynaU7qwjYFb6ZYGXeqstkozXVjCU+feT0MYxh5WuvpwJuJD4LMcbHk n1WA== X-Gm-Message-State: AAQBX9f4fimkrL69C9h7GZcJUXop6fDgPduFgvceBYXjT7T7DJ/OFwVA WZdtV4tgwNW05ildxd/JH8gfH8xKSenmaMbB X-Google-Smtp-Source: AKy350Y8WGtJv5wxaytzfKnKlxt10iAfzKZBoBbyFn4WF437gd6aXmlYDb8KK6m+3I5auaqd4e3K7Ex+rHzIvu5H X-Received: from yosry.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:2327]) (user=yosryahmed job=sendgmr) by 2002:a81:b617:0:b0:541:7f69:aa8b with SMTP id u23-20020a81b617000000b005417f69aa8bmr12492986ywh.5.1680246506838; Fri, 31 Mar 2023 00:08:26 -0700 (PDT) Date: Fri, 31 Mar 2023 07:08:18 +0000 In-Reply-To: <20230331070818.2792558-1-yosryahmed@google.com> Mime-Version: 1.0 References: <20230331070818.2792558-1-yosryahmed@google.com> X-Mailer: git-send-email 2.40.0.348.gf938b09366-goog Message-ID: <20230331070818.2792558-4-yosryahmed@google.com> Subject: [PATCH v3 3/3] mm: vmscan: ignore non-LRU-based reclaim in memcg reclaim From: Yosry Ahmed To: Andrew Morton , Alexander Viro , "Darrick J. Wong" , Christoph Lameter , David Rientjes , Joonsoo Kim , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, "Matthew Wilcox (Oracle)" , Miaohe Lin , David Hildenbrand , Johannes Weiner , Peter Xu , NeilBrown , Shakeel Butt , Michal Hocko , Yu Zhao , Dave Chinner Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org, Yosry Ahmed Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org We keep track of different types of reclaimed pages through reclaim_state->reclaimed, and we add them to the reported number of reclaimed pages. For non-memcg reclaim, this makes sense. For memcg reclaim, we have no clue if those pages are charged to the memcg under reclaim. Slab pages are shared by different memcgs, so a freed slab page may have only been partially charged to the memcg under reclaim. The same goes for clean file pages from pruned inodes (on highmem systems) or xfs buffer pages, there is no simple way to currently link them to the memcg under reclaim. Stop reporting those freed pages as reclaimed pages during memcg reclaim. This should make the return value of writing to memory.reclaim, and may help reduce unnecessary reclaim retries during memcg charging. Generally, this should make the return value of try_to_free_mem_cgroup_pages() more accurate. In some limited cases (e.g. freed a slab page that was mostly charged to the memcg under reclaim), the return value of try_to_free_mem_cgroup_pages() can be underestimated, but this should be fine. The freed pages will be uncharged anyway, and we can charge the memcg the next time around as we usually do memcg reclaim in a retry loop. Signed-off-by: Yosry Ahmed --- mm/vmscan.c | 30 +++++++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index a3e38851b34ac..bf9d8e175e92a 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -533,7 +533,35 @@ EXPORT_SYMBOL(mm_account_reclaimed_pages); static void flush_reclaim_state(struct scan_control *sc, struct reclaim_state *rs) { - if (rs) { + /* + * Currently, reclaim_state->reclaimed includes three types of pages + * freed outside of vmscan: + * (1) Slab pages. + * (2) Clean file pages from pruned inodes. + * (3) XFS freed buffer pages. + * + * For all of these cases, we have no way of finding out whether these + * pages were related to the memcg under reclaim. For example, a freed + * slab page could have had only a single object charged to the memcg + * under reclaim. Also, populated inodes are not on shrinker LRUs + * anymore except on highmem systems. + * + * Instead of over-reporting the reclaimed pages in a memcg reclaim, + * only count such pages in system-wide reclaim. This prevents + * unnecessary retries during memcg charging and false positive from + * proactive reclaim (memory.reclaim). + * + * For uncommon cases were the freed pages were actually significantly + * charged to the memcg under reclaim, and we end up under-reporting, it + * should be fine. The freed pages will be uncharged anyway, even if + * they are not reported properly, and we will be able to make forward + * progress in charging (which is usually in a retry loop). + * + * We can go one step further, and report the uncharged objcg pages in + * memcg reclaim, to make reporting more accurate and reduce + * under-reporting, but it's probably not worth the complexity for now. + */ + if (rs && !cgroup_reclaim(sc)) { sc->nr_reclaimed += rs->reclaimed; rs->reclaimed = 0; }