From mboxrd@z Thu Jan 1 00:00:00 1970 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id F0649F41807 for ; Mon, 9 Mar 2026 15:08:33 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4EB316B0088; Mon, 9 Mar 2026 11:08:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4B61E6B0089; Mon, 9 Mar 2026 11:08:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3CCB16B008C; Mon, 9 Mar 2026 11:08:33 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 2DE4A6B0088 for ; Mon, 9 Mar 2026 11:08:33 -0400 (EDT) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id C18C75739A for ; Mon, 9 Mar 2026 15:08:32 +0000 (UTC) X-FDA: 84526856064.24.50D152D Received: from mail-wm1-f48.google.com (mail-wm1-f48.google.com [209.85.128.48]) by imf01.hostedemail.com (Postfix) with ESMTP id 7D5D54000A for ; Mon, 9 Mar 2026 15:08:30 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=suse.com header.s=google header.b=XscvnJC7; spf=pass (imf01.hostedemail.com: domain of mkoutny@suse.com designates 209.85.128.48 as permitted sender) smtp.mailfrom=mkoutny@suse.com; dmarc=pass (policy=quarantine) header.from=suse.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1773068910; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding:in-reply-to: references:dkim-signature; bh=mjuuwRMRXMuBEkBAokG0kVZoWPUDTpeuLcxt/9gKsig=; b=VwZmku477sxDZgCidWqfWUxNc7D/ApyR0Htqvb3LapA1BMZvbMb7TCduZCgxbNy44ERzzP B5elZ+YQGkAEQ5rD7xi8BKq6wtEgWu9hUQtjGJXZxtceaqjbAJPfqHmaSWuedzkdhYIn9+ VMnvpUQozdwVITZhdQK8ghDz26m1vjo= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1773068910; a=rsa-sha256; cv=none; b=phsDg/bZDrOXMq2Gii4F2PaQXe/+8MyOgCNSuZmdG/2dgO64kQB9CUqLvr9sEGAUvRsI/T SqdLT2ya46l/mDzOb9tC6E45QeDsnL7ApzJWwME+29xeecnr1yTGnR+kI7A7LPwi/RHIuM rYaMWWJH1U0dE4wM2LhlKzaHdvwoWLo= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=suse.com header.s=google header.b=XscvnJC7; spf=pass (imf01.hostedemail.com: domain of mkoutny@suse.com designates 209.85.128.48 as permitted sender) smtp.mailfrom=mkoutny@suse.com; dmarc=pass (policy=quarantine) header.from=suse.com Received: by mail-wm1-f48.google.com with SMTP id 5b1f17b1804b1-48540355459so5340375e9.3 for ; Mon, 09 Mar 2026 08:08:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1773068909; x=1773673709; darn=kvack.org; h=cc:to:message-id:content-transfer-encoding:mime-version:subject :date:from:from:to:cc:subject:date:message-id:reply-to; bh=mjuuwRMRXMuBEkBAokG0kVZoWPUDTpeuLcxt/9gKsig=; b=XscvnJC7k9OnomiCvfD/aji3paKJTQ4DSYV0rkEvOXOzVausrAa55/ry0hJgvDPJpB Mgq68ZnTOuoyiBlY/PIU2pPD9Vc9PiCzmnhGzJ3zNeGAJPeqjWkDckTLHwAJibXhI3QC XwyzFM7aI/r6lpynT1gzdPcrLGw/m2fDOzOm5taWJA9sR3Em/uGh2WVJGugTtszLKq2P ZLdAPtH2BJ9StvLZwA4jZJnkrh/7I6bm/uu4yo6DSQ5ln9hHsywbNBug3PrKE5CUjWSI DB2U8BsxIDAHA2XXxcd4cxenDZDvGO5gXWFxqGFnUa3bhMMjFTdqM5oz+sJsyVn2Zdu3 To5Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1773068909; x=1773673709; h=cc:to:message-id:content-transfer-encoding:mime-version:subject :date:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=mjuuwRMRXMuBEkBAokG0kVZoWPUDTpeuLcxt/9gKsig=; b=RCR76kfMGe7XMPSjgwnIxCrVcbN7cPuMIsvn91VRqTS9+Fw5nxrkh9jTTvNQG0mswq bX4/df1MFXcp/Gutw3R4mhmuKsFua8YStZI4sf57TXaIKmPodpESDjlaP4J9oP3/CKmu YUvoj+C9lCO7V7CCBXyXtje8pJw5pg2V1TaNFmXbZKF63N7ANxZoqEp11948hn7roc8D aiYf6P+JBh45WQeBQDfrbfHHmGhigRWDZnvebfDsajT6GAdWijGqng/rpMFcYbLaBqih VzkfNGPCvuziFKKIIOoboQcrNA5lS/hs1rFlMmD8z73rlIhFLvnpbH9yOG9x0WlQZEJj inLg== X-Forwarded-Encrypted: i=1; AJvYcCUjct2wRilyqg9eZ0vufBmlzggXiDJjiVGhWDcrJGY1BOmhobk9R5t+UJXGmAjefawIWMfLUTDY4g==@kvack.org X-Gm-Message-State: AOJu0Yy/Z0zZm6D78inShsg+i+s3IImlI7iotFno82G2mAdLlyVhWJaK MyYccT2XlLUwWNYmT60bMGlITD1x99yzc8zuy5JBoCY0JMsZ/efLFtKP7ZBnUSpIPbwEsjmnugI 0krvO X-Gm-Gg: ATEYQzyUdFomYu0/vxxC+fmc9PlYoeX/mv4zItBC9y2lnPE+DMKLaZfc0gsofFQu/Xl KxUoorj/8Kf3RxtC9uqu+uYVTa1QyfcQMuRi9s51fXy4hyeI6zVn3FdumMuCMiJdINCQRLJJUrr aJvNrevy6+J4j7xoBP+8crvhKD+UfDL0QNevS4mRpK0yjf8cooXxw8btuu5P026doIg5Lm+DSJB klyVXAqeeArGD2rJUG/ReM0E8iaT2vhXG8PTo7K4J71Vzl/m/WruO1U+6ZmQQ4ydMVQzR0mehLF KLjftwVnjyr2JreeUUUAeh6naqnX+KSNiOqOQID7B8C6/hBaJqOutjxZQh6EoXJP1/AsLnF4D3O wAJz2NYzPr3gtZ4efhCIgR5P9Xa7IAAeWqbFmijCztIJUSX44uCT2LMC2pI29JKR4VtWytzRVgk gxG63kQbI2AH4gZzDw3mllyZ928KrOtnTnS1zEcDrNJ6c= X-Received: by 2002:a05:600c:6306:b0:485:40ed:2d1 with SMTP id 5b1f17b1804b1-48540ed03fdmr14531205e9.17.1773068908685; Mon, 09 Mar 2026 08:08:28 -0700 (PDT) Received: from blackdock.suse.cz (nat2.prg.suse.com. [195.250.132.146]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-439dad8da01sm28684927f8f.1.2026.03.09.08.08.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Mar 2026 08:08:28 -0700 (PDT) From: =?utf-8?q?Michal_Koutn=C3=BD?= Date: Mon, 09 Mar 2026 16:08:08 +0100 Subject: [PATCH v2] mm: Do not allocate shrinker info with cgroup.memory=nokmem MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Message-Id: <20260309-cgroup-ml-nokmem-shrinker-v2-1-3e7a7eefb6c9@suse.com> X-B4-Tracking: v=1; b=H4sIAFfirmkC/42NTQ6CMBBGr0Jm7RgYfwBX3sOwgHYKE2xLWiEaw t2tnMDl+5LvvRUiB+EIt2yFwItE8S4BHTJQQ+t6RtGJgXK65kQXVH3w84T2ic6Pli3GIYgbOWC p2zOZTpnKEKT/FNjIe3c/msSDxJcPnz21FL/1H+tSYIG6zE9VXXc6Je5xjnxU3kKzbdsXp5Wol sEAAAA= X-Change-ID: 20260225-cgroup-ml-nokmem-shrinker-7da42fbcf8f2 To: Andrew Morton , Dave Chinner , Qi Zheng , Roman Gushchin , Muchun Song Cc: Jan Kara , linux-mm@kvack.org, linux-kernel@vger.kernel.org, =?utf-8?q?Michal_Koutn=C3=BD?= X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=2455; i=mkoutny@suse.com; h=from:subject:message-id; bh=PF7PEPuBVFEev9rRlZplgRHqFt2dHhMGKiCN80nPSv0=; b=owGbwMvMwCVWZ8v0fMrtHxyMp9WSGDLXPUo7IhO6X+rd1bAl3syOVw64fv6zKWBh/qo13sXl2 6vcH/y075jIwiDGxWAppsjiJJzHOv+DjJvl6a4vMHNYmUCGSIs0MAABCwNfbmJeqZGOkZ6ptqGe IZChY8TAxSkAU11jzvCH33/risv7sgOdm590TbQulDR4aWJVzntyxapwKVtTtrQ1jAxnmvhWXne JPlO8YcG3+bcyo89Fl7ryq23ZtJlH+uLaR1XMAA== X-Developer-Key: i=mkoutny@suse.com; a=openpgp; fpr=9F2AB6F1F2BBEE7621C1B620CFDED9A2FD1314F0 X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 7D5D54000A X-Stat-Signature: pnyzq9ahmykodg1oedc6q5n66amks7n4 X-HE-Tag: 1773068910-905144 X-HE-Meta: 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 1QHGJnCe 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: There'd be no work for memcg-aware shrinkers when kernel memory is not accounted per cgroup, so we can skip allocating per memcg shrinker data. This saves some memory, avoids holding shrinker_mutex with O(nr_memcgs) and saves work in shrink_slab_memcg(). Then there are SHRINKER_NONSLAB shrinkers which handle non-kernel memory so nokmem should not disable their per-memcg behavior. Such shrinkers (e.g. deferred_split_shrinker) still need access to per-memcg data (see also commit 0a432dcbeb32e ("mm: shrinker: make shrinker not depend on memcg kmem")). The savings with this patch come on container hosts that create many superblocks (each with own shrinker) but tracking and processing per-memcg data is pointless with nokmem (shrink_slab_memcg() is partially guarded with !memcg_kmem_online already). The patch uses "boottime" predicate mem_cgroup_kmem_disabled() (not memcg_kmem_online()) to avoid mistakenly un-MEMCG_AWARE-ing shrinkers registered before first non-root memcg is mkdir'd. Reviewed-by: Muchun Song Acked-by: Qi Zheng Reviewed-by: Roman Gushchin Signed-off-by: Michal Koutný --- Changes in v2: - update comment (Qi) - collect trailers - rebase on master - Link to v1: https://lore.kernel.org/r/20260225-cgroup-ml-nokmem-shrinker-v1-1-d703899bdda4@suse.com --- mm/shrinker.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/shrinker.c b/mm/shrinker.c index 7b61fc0ee78fb..167cd70ae4918 100644 --- a/mm/shrinker.c +++ b/mm/shrinker.c @@ -219,6 +219,8 @@ static int shrinker_memcg_alloc(struct shrinker *shrinker) if (mem_cgroup_disabled()) return -ENOSYS; + if (mem_cgroup_kmem_disabled() && !(shrinker->flags & SHRINKER_NONSLAB)) + return -ENOSYS; mutex_lock(&shrinker_mutex); id = idr_alloc(&shrinker_idr, shrinker, 0, 0, GFP_KERNEL); @@ -716,6 +718,7 @@ struct shrinker *shrinker_alloc(unsigned int flags, const char *fmt, ...) * - non-memcg-aware shrinkers * - !CONFIG_MEMCG * - memcg is disabled by kernel command line + * - non-slab shrinkers: when memcg kmem is disabled */ size = sizeof(*shrinker->nr_deferred); if (flags & SHRINKER_NUMA_AWARE) --- base-commit: 1f318b96cc84d7c2ab792fcc0bfd42a7ca890681 change-id: 20260225-cgroup-ml-nokmem-shrinker-7da42fbcf8f2 Best regards, -- Michal Koutný