From patchwork Tue Apr 4 00:13:51 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yosry Ahmed X-Patchwork-Id: 13198927 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 84B0BC77B70 for ; Tue, 4 Apr 2023 00:14:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229576AbjDDAOB (ORCPT ); Mon, 3 Apr 2023 20:14:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41210 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230527AbjDDAN7 (ORCPT ); Mon, 3 Apr 2023 20:13:59 -0400 Received: from mail-pl1-x64a.google.com (mail-pl1-x64a.google.com [IPv6:2607:f8b0:4864:20::64a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 999273C07 for ; Mon, 3 Apr 2023 17:13:58 -0700 (PDT) Received: by mail-pl1-x64a.google.com with SMTP id u11-20020a170902e80b00b001a043e84bdfso18618087plg.23 for ; Mon, 03 Apr 2023 17:13:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1680567238; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=/hxuqZFO5U+CmKAu0Izd1qiRBhW4afUnD0WyfUo4Gcw=; b=ERBMFlpwQ+/e/a/Z3AL8E+p3U9MNbkZrsz1HL/MZqvfsps00VtVZYbkySPDVq2/6aR LHVdBQe3ElTtHckYtN+0h+FDNuiI47HZzvKorWDJwFV06A2ZOZ9rTLgMNb03YVp2wZvD PgyPdh7s9QF5a+LrPpjkbUaqX5VHdnehZzbSO8EQsnkGFGX9ApbhWI2WH3GTZIdOCnMl aWLwqKHsahq90y7bzc7mLyA1MCyJjLXiPgYUQBEdJC8xf/8EamW1fLH2Ww2pGZUCTg1p jUEPpHXUbx3wFMtNPW+KmYfxXVLvMYfkOtlZrUyDZokuwj17Ht/6/tV/rlF0tPwOfpWA Gsag== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680567238; 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=/hxuqZFO5U+CmKAu0Izd1qiRBhW4afUnD0WyfUo4Gcw=; b=itJKr8jxwuN4j6jTn6fvarWJJYRbuHfgELq86XNInAWqbdVtbo4htFiP/I58XyUA7G cs2BKJkgtQM597EUW7idJ4R/oyGmCSYzuOShO7lEXkhGIjdA5u2RTCCStCgF+XWLTgjd u8BUHPlwZ3ZM3LyNdf3e3kHmkafxL4/Dp91o4L9Ejp6X5+NQdWklqLSw8r+H3Iyw0cVQ DhvEkUVwEQcQvTryOHIcmAIQOvIKOT9obQ98ucQU0t4zl9QzEO7vBjuUjXeaZmS9UT1g GPOvWJiEY6IydByrMf1i1D9JMATooMk3+8kAZibsygsqFWzJXlK7xLvvX3GEQRj9BPx5 m9TA== X-Gm-Message-State: AAQBX9dKKPnRV3ze5gOyfDUeRpW7u/9iFr9AbNWSmSqXnqEn8gIKkO4s WC0fHet5j6XHAr7xjx+AsRxKYWpe9dNXGdAV X-Google-Smtp-Source: AKy350Z+Sm8hAQJcQhRAP+xzVs9NeoT30dH7npmf11D1Z/F0xl2wPw5f56Q84WDvH4pUeUa2sdKUL4OGwZiD1m0K X-Received: from yosry.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:2327]) (user=yosryahmed job=sendgmr) by 2002:a05:6a00:23cd:b0:625:5949:6dc0 with SMTP id g13-20020a056a0023cd00b0062559496dc0mr232232pfc.4.1680567238017; Mon, 03 Apr 2023 17:13:58 -0700 (PDT) Date: Tue, 4 Apr 2023 00:13:51 +0000 In-Reply-To: <20230404001353.468224-1-yosryahmed@google.com> Mime-Version: 1.0 References: <20230404001353.468224-1-yosryahmed@google.com> X-Mailer: git-send-email 2.40.0.348.gf938b09366-goog Message-ID: <20230404001353.468224-2-yosryahmed@google.com> Subject: [PATCH v4 1/3] mm: vmscan: move set_task_reclaim_state() after global_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 global_reclaim() is defined. We are about to add some more helpers that operate on reclaim_state, and will need to use global_reclaim(). Move set_task_reclaim_state() after the #ifdef CONFIG_MEMCG block containing the definition of global_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 Tue Apr 4 00:13:52 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yosry Ahmed X-Patchwork-Id: 13198928 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 B50CEC76196 for ; Tue, 4 Apr 2023 00:14:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231794AbjDDAOJ (ORCPT ); Mon, 3 Apr 2023 20:14:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41258 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231695AbjDDAOB (ORCPT ); Mon, 3 Apr 2023 20:14:01 -0400 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 87412A6 for ; Mon, 3 Apr 2023 17:14:00 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-5463f2d3223so133723367b3.14 for ; Mon, 03 Apr 2023 17:14:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1680567240; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=KttjkMRwWn+raVJD4pdmRR27zCHPUdxyxHHqMjZ4zso=; b=LtYxh8YfdBOctNDOeOLcBvNxi7r6sZaIjGKGM0dSm4YAneG6TwPyrn6ciNpFpw7o05 agIDp8r5g1zsrBgbrkIAj0istxDrIlFVjEGnPtfdwxO+fsBcrB9rTcH6hnSDhjeSGcI9 DNWZ+jLmPaIMNrbRgwWvkKyl3KncBlpUe/ySEPbtedlDu2Al/e4kMdIq0CbOxcu1yZTM p4hiQCl8bRdPl3Qg3dXxTrvvyXCgzXh5Si+jrlA5hVfiT0NfHjRVSIoyov4AHA/OntzE adXxHHHwpx/tQEJ5noRB+DDraQeehxLQoOxrCnjR60/cYEdTl8ijh1e5DVzefIts+Ack bxFA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680567240; 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=KttjkMRwWn+raVJD4pdmRR27zCHPUdxyxHHqMjZ4zso=; b=OjFRYwXS+9ZvLMeYGslny1+p7ZrZZRF67IUe4EJsrWYjx6UVOiQ53qWAT8Qu593+38 XL7kAvCApqW6UuWgMDG+E5lniByk+DfIhcFOLIF1t9UIP40urcQQL++K1Z6uUX2vaZtE PE1NzS+WGQChAnwJY/RKtNOP1VLf0pygsLT1xaZ732ch/m8D5ar5p1jHJXvV9b79lcFK 9hBBm3mHckQGDZ8dxlniy3EiZRQOiDV0h43l5+Ea2zG5xAwszDutMYKURss5UcvytaFj nGUpMD2QWrJW9/2G+KCzkx6WzcxLzttvTJczM5SjYezZ/I1+KUqZdYsn/sQoqFUYCTC5 7efA== X-Gm-Message-State: AAQBX9eoOmtNT2qllO6jL7qmw35Zd4ErpzPj6C84MPMPQrDVyuERlVWm 8zsfZ06JFwhGlga0R6EMrSgBC3gxnKR8Hda+ X-Google-Smtp-Source: AKy350aw2fB9OoYuquCgQGUwaaV+x9FcDRGjxrCFXXINr0QvKI17cucoPmiPUl1lnvL0dNkgmm2U7bqUVOt3NxkG X-Received: from yosry.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:2327]) (user=yosryahmed job=sendgmr) by 2002:a25:d950:0:b0:b7d:87f:ce3e with SMTP id q77-20020a25d950000000b00b7d087fce3emr663961ybg.6.1680567239851; Mon, 03 Apr 2023 17:13:59 -0700 (PDT) Date: Tue, 4 Apr 2023 00:13:52 +0000 In-Reply-To: <20230404001353.468224-1-yosryahmed@google.com> Mime-Version: 1.0 References: <20230404001353.468224-1-yosryahmed@google.com> X-Mailer: git-send-email 2.40.0.348.gf938b09366-goog Message-ID: <20230404001353.468224-3-yosryahmed@google.com> Subject: [PATCH v4 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 | 17 ++++++++++++++++- mm/slab.c | 3 +-- mm/slob.c | 6 ++---- mm/slub.c | 5 ++--- mm/vmscan.c | 21 +++++++++++++++------ 7 files changed, 38 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..e131ac155fb95 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -153,13 +153,28 @@ 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 }; +/* + * 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. + */ +static inline void mm_account_reclaimed_pages(unsigned long pages) +{ + if (current->reclaim_state) + current->reclaim_state->reclaimed += 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..8f0e7c4e91ae3 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -511,6 +511,19 @@ static void set_task_reclaim_state(struct task_struct *task, task->reclaim_state = rs; } +/* + * 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 +5359,7 @@ 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 +6484,7 @@ 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 Tue Apr 4 00:13:53 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yosry Ahmed X-Patchwork-Id: 13198929 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 5D3A0C76188 for ; Tue, 4 Apr 2023 00:14:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231906AbjDDAOQ (ORCPT ); Mon, 3 Apr 2023 20:14:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41346 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231741AbjDDAOE (ORCPT ); Mon, 3 Apr 2023 20:14:04 -0400 Received: from mail-pj1-x104a.google.com (mail-pj1-x104a.google.com [IPv6:2607:f8b0:4864:20::104a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 47CFF4229 for ; Mon, 3 Apr 2023 17:14:02 -0700 (PDT) Received: by mail-pj1-x104a.google.com with SMTP id ie7-20020a17090b400700b0023f06808981so8021137pjb.8 for ; Mon, 03 Apr 2023 17:14:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1680567242; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=QYyKpmgAe3S55Nk5FWRs2dH0UIocesat7xjNxdFTU4k=; b=W5WukSX7xVU0/vv5ALD+tup9Pddeb9Iipi9kb8kJt/jBn+TQTiZoJyEWgKO/OQ61Jh 2tDeM9kRzvnDYGPtmMlhz5iVehjZJg/jQ63YFUQ7WbbPKq0AY2cM2cHrwogahpd+PgEG XwtqC+dGnvs0z0/3t8FCcMDB2O7fMVf3H3E2qFVcjwb9hPLZO3zgEa2XrTMXRi9MFCHf WEtCE6c9sD8f7AqxvmgV8c+yt8qmrF2I9lAqEvjVuhsI1HciUBrepOGZet31fNCDDW8P oX+wUwY7aO9vBuigwgimgUP/rKThFLYxYAVKIiGShyp9evKm8iqS6ChI4jTiXqDaT7MQ ct3Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680567242; 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=QYyKpmgAe3S55Nk5FWRs2dH0UIocesat7xjNxdFTU4k=; b=u1TvPNC/oiSDBdpCRgh+2Q3211+t+TjreY9GXKh6uke0d7FgTiHzsgyKNaen64MUQC i3CZrR3cquV11Oe6uAFMPxRrcmCmDnEEIY1EtzWs0hGHMEKRQqixQSzrs/IUIJGGG0aU eheQ0kNSO3F9ngV+Du9tSqM3kKsjZsBlCUif8f6JmS/agVPeoRfyPNlACt4/CqiygRE8 sCLR/nRbO5fR10OLKLllPeqjmOQgv8aj5iZ9fS+RXTyjXMV6N+eYg1wcnxbxnNsSjfGn UMzrU98Izv1f6QBW+UhuzWqUPVPADTNsOL3ST0Ldab/Pcrh8Hrw27j9zVINxiYmYavxD eChw== X-Gm-Message-State: AAQBX9e/LySkJ6uhVfEQJXiCF520kYmM2kDU62VAirvJeKjF7eqdFW7i O3iOunhXdj/uNwjOpN9LzOWgL42nAaNfdE6w X-Google-Smtp-Source: AKy350a8jpmup3Y0AoRXTeOyKKcgC2LVL+csu37K+C5/P3dMmovoTexr82+Hd4O52pTXV8PmQrABJAtIr5EvWJJc X-Received: from yosry.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:2327]) (user=yosryahmed job=sendgmr) by 2002:a05:6a00:2e14:b0:627:e6d5:ba2d with SMTP id fc20-20020a056a002e1400b00627e6d5ba2dmr223605pfb.6.1680567241767; Mon, 03 Apr 2023 17:14:01 -0700 (PDT) Date: Tue, 4 Apr 2023 00:13:53 +0000 In-Reply-To: <20230404001353.468224-1-yosryahmed@google.com> Mime-Version: 1.0 References: <20230404001353.468224-1-yosryahmed@google.com> X-Mailer: git-send-email 2.40.0.348.gf938b09366-goog Message-ID: <20230404001353.468224-4-yosryahmed@google.com> Subject: [PATCH v4 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. Writing to memory.reclaim on the root memcg is considered as cgroup_reclaim(), but for this case we want to include any freed pages, so use the global_reclaim() check instead. 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 8f0e7c4e91ae3..049e39202e6ce 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -518,7 +518,35 @@ static void set_task_reclaim_state(struct task_struct *task, 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 global 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 && global_reclaim(sc)) { sc->nr_reclaimed += rs->reclaimed; rs->reclaimed = 0; }