From patchwork Thu Mar 9 09:31:07 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yosry Ahmed X-Patchwork-Id: 13167114 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 71628C74A4B for ; Thu, 9 Mar 2023 09:31:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229913AbjCIJbc (ORCPT ); Thu, 9 Mar 2023 04:31:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41202 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230423AbjCIJba (ORCPT ); Thu, 9 Mar 2023 04:31:30 -0500 Received: from mail-pj1-x1049.google.com (mail-pj1-x1049.google.com [IPv6:2607:f8b0:4864:20::1049]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 040EA32505 for ; Thu, 9 Mar 2023 01:31:29 -0800 (PST) Received: by mail-pj1-x1049.google.com with SMTP id mp16-20020a17090b191000b0023ab4b5b064so885372pjb.9 for ; Thu, 09 Mar 2023 01:31:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1678354288; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=o6dgxagOpBb1myYnk/1Y2AGrRWWDZLYTueWoLu8qIY4=; b=KzU6h4ueyt1nc3fHTw62ynzTN6cM5FPoDfMBmAqJ1Wwes61zVej5BOhlYyPncxm4Zm nkjKeBNIQMZU0E9YJO2405czXqReQIP71dpM6JRcIVBwGfbOfnDAO+93r67dHWvV1VcL zONddPvKo2/hWkzUIRnhDO3Zqp+7yh7T+acFffATa66sYzOvTr15BMFihxW3t2a2tMq/ 8Ig75rYkpQRqgddwtZBlA3k3y0eMCsf3xzOYsCI2yvjWMp0avrLAbOSW5a+OH2FI5iL+ ETd/0TFbN+DnBMOE/8xtP1qGx1HOTcBW/q+JbvhFqWJVi18NNllY9Hag5hM4SObpgkS6 mKfA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1678354288; 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=o6dgxagOpBb1myYnk/1Y2AGrRWWDZLYTueWoLu8qIY4=; b=LGUKt2LTAP99QNsM2EAgCoLTxEwGbq+Ar6RRa7hOVr3IimZBDJls94b8qEgfgTJsZj +kymrvM1dyl1avMhLHjxGDQghpMPiNEMsZzj7EcMX0MKM0ktoxS2eAbg1ERyFAp5L8G3 Ion7oE9ugxGkPRD6JypB2H+uQiWefUFkeTK6XCXfpKIuLOUt3MWlH2mQdcQWF730MNgJ +E+yTAaY1qfx8cDWElMybgkUrYKIrErJNG1cVZqZeZm4dQ+DZ60bAfJJvXYg95SAiH7G EbCMpjchxmTuJiuC38i2KRyS44jUQmOBEIoo0d1E1r6VoUjp9FT57ZU5+cQPBOPUNPcw +nIA== X-Gm-Message-State: AO0yUKUjPn13QsFdSFwJdjiRm7Pl8Fl1SxlU8SOBoBBCmaPnK2nBlrZo +PiAV36BKAOz4ZiKu8waj/yoXxw8YQMfS30l X-Google-Smtp-Source: AK7set82CEBSuqo8FpS3nsNPKqDoN9u1SA11kEpTwZaYFka9KSS8D9zMVtgu+8uzsp90VdIxYuFl/oAa7auTdfM+ X-Received: from yosry.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:2327]) (user=yosryahmed job=sendgmr) by 2002:a63:5508:0:b0:502:fd71:d58c with SMTP id j8-20020a635508000000b00502fd71d58cmr7728137pgb.9.1678354288447; Thu, 09 Mar 2023 01:31:28 -0800 (PST) Date: Thu, 9 Mar 2023 09:31:07 +0000 In-Reply-To: <20230309093109.3039327-1-yosryahmed@google.com> Mime-Version: 1.0 References: <20230309093109.3039327-1-yosryahmed@google.com> X-Mailer: git-send-email 2.40.0.rc0.216.gc4246ad0f0-goog Message-ID: <20230309093109.3039327-2-yosryahmed@google.com> Subject: [PATCH v2 1/3] mm: vmscan: move set_task_reclaim_state() after cgroup_reclaim() From: Yosry Ahmed To: 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 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 9c1c5e8b24b8..fef7d1c0f82b 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 Thu Mar 9 09:31:08 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yosry Ahmed X-Patchwork-Id: 13167115 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 589B3C61DA4 for ; Thu, 9 Mar 2023 09:31:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231192AbjCIJbg (ORCPT ); Thu, 9 Mar 2023 04:31:36 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41278 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230508AbjCIJbd (ORCPT ); Thu, 9 Mar 2023 04:31:33 -0500 Received: from mail-pf1-x449.google.com (mail-pf1-x449.google.com [IPv6:2607:f8b0:4864:20::449]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BF8C4A1FE9 for ; Thu, 9 Mar 2023 01:31:31 -0800 (PST) Received: by mail-pf1-x449.google.com with SMTP id h1-20020a62de01000000b005d943b97706so950307pfg.0 for ; Thu, 09 Mar 2023 01:31:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1678354291; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=h6SnRTgbJt8uctknxsPWdjBgy9HatQBYNy5scoYuFng=; b=BIspgDfgpDn4bkLxtBabsOU9Uhv4DiqHmpsyEYFdYYQOsugC1O3FyPc6aDReE1SUAN 5uV0uFO+sQlWKI/40WV3HZDPsDyksERJrVxwFRis6lKh0WsNGujWmErL0jVg9DFJ7Sxd IuVjwB/VEOvIqca+ISasnf6kTvYtPtyS5xSUuEuv0nl1KwuTEi21GUVG3fYoJYL/P/IC HyKUQOiXj+7FJ83bqgaNXvvsRkza48cZcoJSntHuv6rgRw6VPmYf64OIgEh4BzpyXPFS xbI1nWERtwBhK1R2RwjpugpOVd7LTuQKHDFNUS6dv8MWFgB5hNM2IG1rMMNwqORxP1qi hAOQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1678354291; 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=h6SnRTgbJt8uctknxsPWdjBgy9HatQBYNy5scoYuFng=; b=LJfdvZ0w4pwiJcUSrPV3TXGbTo28gZuyOHruLVFa63WfJzpoPga/nfAPXkAgFqHgx/ iv8XxxFsNF5Wbyn9xnitV693Ks7rv8mqcm3DmsJWWMePrSxdGF0tinEW2s1Ng4I7rrjW oLPMWwoOoDmfgmRcNLO7nHf1vxxl3sP2cSXNdj3eqCcT1pUrTzfwFGmBk9KDu9YB7KwO FEbhw4F2GrBPDhiskdIzreiz5/mszcA6X08mgy9tXqykV2M/JJublOyNIFuBD0l/5Nvc iSH+dyMgJEOdWp+bh3mVwV/xoV96/7RxcPEXZBPybiPFoC5juqTkQEsG2sJKfIywngRG SHdw== X-Gm-Message-State: AO0yUKWN2gJTWqjzyLfs2K3hXWs0uBzz41oribIFqohGh+siNNatEYCu nI70B/XS71RneEq5p4+nQHPMDzYjaeG9ys9x X-Google-Smtp-Source: AK7set/xvyeflSxZY0dqmtHjFakw/c6fvI1rhtdCuvGq7DrJIicLLxLjDK/zNls11ytQyWAWIJilVYP0U74iRmT+ X-Received: from yosry.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:2327]) (user=yosryahmed job=sendgmr) by 2002:a17:902:ef8a:b0:19a:9434:af24 with SMTP id iz10-20020a170902ef8a00b0019a9434af24mr8176829plb.10.1678354291238; Thu, 09 Mar 2023 01:31:31 -0800 (PST) Date: Thu, 9 Mar 2023 09:31:08 +0000 In-Reply-To: <20230309093109.3039327-1-yosryahmed@google.com> Mime-Version: 1.0 References: <20230309093109.3039327-1-yosryahmed@google.com> X-Mailer: git-send-email 2.40.0.rc0.216.gc4246ad0f0-goog Message-ID: <20230309093109.3039327-3-yosryahmed@google.com> Subject: [PATCH v2 2/3] mm: vmscan: refactor updating reclaimed pages in reclaim_state From: Yosry Ahmed To: 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 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 4558dc2f1355..e60fcc41faf1 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 54c774af6e1c..060079f1e966 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; + report_freed_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 209a425739a9..589ea2731931 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 dabc2a671fc6..64bf1de817b2 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 fe567fcfa3a3..79cc8680c973 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 39327e98fce3..7aa30eef8235 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 fef7d1c0f82b..a3e38851b34a 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 Thu Mar 9 09:31:09 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yosry Ahmed X-Patchwork-Id: 13167116 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 32BACC64EC4 for ; Thu, 9 Mar 2023 09:32:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231272AbjCIJcF (ORCPT ); Thu, 9 Mar 2023 04:32:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41430 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230465AbjCIJbh (ORCPT ); Thu, 9 Mar 2023 04:31:37 -0500 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 C4D0AA1FE9 for ; Thu, 9 Mar 2023 01:31:35 -0800 (PST) Received: by mail-pl1-x649.google.com with SMTP id t24-20020a1709028c9800b0019eaa064a51so827666plo.10 for ; Thu, 09 Mar 2023 01:31:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1678354295; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=LEwBMGSn5GpbGlanBqXFsfdHu3Z53NaeJ1a3nMwnQiU=; b=Ze5OIdzu8ujFo9cbq83YqFk9GJOpYr3a3BQKfOSfr4rWI6Yo1wqOYG0VZvkRQl/DgU ONZDb780V2AJLPqQWE3i1IZDOj2DrlnYx2p9SESApSRJk73I5fI+TzBG7cY4phGhOfvE fsxBi+Mbo+Sti9UuMrxl9QnG0QjPUVEa7+s1cz+Q3wYagCiAWB2+bxT6WbOhwW63YCyL vx4QV8MkTkeQi+EJ1ehIcECB6ITq43CvVn8IyyqwmqR4ySJXDiat0u00fzVgzef7Kjx0 9ui6RevSQ/etQzip+tetVSB6hNPcbI8D0n9SoMlj9xGPz0n+yHL+qWibozRsuDEXX+zi /5CQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1678354295; 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=LEwBMGSn5GpbGlanBqXFsfdHu3Z53NaeJ1a3nMwnQiU=; b=T/rOx80ORcCaRlTWuyqg3Kj0v9oRON7y8bvnMUdwiYGNI9fBTGdO8QPd/JOa+fwuf5 REH/I6Zj9z3F2+oCdfOARII9ywJCi8VQE0RBGcISBn7U9Mbxn20bh7ojVgmiJfSNjoRe Kp6fOaWvPvIzlsocUgxQFrWLryrA2K4JfvjJTGbiQpmdG6b5GzBrXn1WoSByJAyioV+E Zj1qEdxdPXTohn8cs6cfoFve72XFUwxYOmhMoP7uVz8depvKRkWBqtpxn5rpJXkJvORv 9ghOg+7Uk6S1q19fBREMnJHLBJo6cl9ePp6NuzWuiqyn3h+NvM/tav9p5m7Uu3VvVUiI 2IfA== X-Gm-Message-State: AO0yUKXhwhuBTybcmEFIkBFf+FT0LyAdpfLebAN3kSOEu8e0eKBjdxHX 5jFvA+AvbykZgg1goDhPZjdOwWrbZgUrFvdh X-Google-Smtp-Source: AK7set/0zSElUk4SV6Jx9e5eK8m600vzb0RCF1MUNHWJepBbU4SjCTMuv6lVZNxTeTFxx/o7bLiMKSNeOfppeLHP X-Received: from yosry.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:2327]) (user=yosryahmed job=sendgmr) by 2002:a63:2953:0:b0:502:ecb9:4f23 with SMTP id bu19-20020a632953000000b00502ecb94f23mr7361890pgb.5.1678354295295; Thu, 09 Mar 2023 01:31:35 -0800 (PST) Date: Thu, 9 Mar 2023 09:31:09 +0000 In-Reply-To: <20230309093109.3039327-1-yosryahmed@google.com> Mime-Version: 1.0 References: <20230309093109.3039327-1-yosryahmed@google.com> X-Mailer: git-send-email 2.40.0.rc0.216.gc4246ad0f0-goog Message-ID: <20230309093109.3039327-4-yosryahmed@google.com> Subject: [PATCH v2 3/3] mm: vmscan: ignore non-LRU-based reclaim in memcg reclaim From: Yosry Ahmed To: 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 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 a3e38851b34a..bf9d8e175e92 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; }