From patchwork Fri Mar 14 06:15:07 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shakeel Butt X-Patchwork-Id: 14016307 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]) by smtp.lore.kernel.org (Postfix) with ESMTP id CB34DC35FF1 for ; Fri, 14 Mar 2025 06:15:48 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 417A1280009; Fri, 14 Mar 2025 02:15:47 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 37A36280003; Fri, 14 Mar 2025 02:15:47 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1F40B280009; Fri, 14 Mar 2025 02:15:47 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id EC11C280003 for ; Fri, 14 Mar 2025 02:15:46 -0400 (EDT) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id BB0C21A0ACC for ; Fri, 14 Mar 2025 06:15:47 +0000 (UTC) X-FDA: 83219145534.19.E797040 Received: from out-182.mta1.migadu.com (out-182.mta1.migadu.com [95.215.58.182]) by imf11.hostedemail.com (Postfix) with ESMTP id E834C40004 for ; Fri, 14 Mar 2025 06:15:45 +0000 (UTC) Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=V274faEo; spf=pass (imf11.hostedemail.com: domain of shakeel.butt@linux.dev designates 95.215.58.182 as permitted sender) smtp.mailfrom=shakeel.butt@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1741932946; 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-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=tHvct7NUO2otKVtcPkikbwH9IxeqmMsC6tyfV+hMsCI=; b=5Q8DSrKHCgMr5hM7W6XFLsazdUbUSXy8vMcEGV7axdT1oFTsfEQjxl41viymS6sGnT90+V H6TBhvd3wc92cd6Lb4knC5oS88zXBh/KWPcY62jR3FlbNkJvQwRxfRhw71reb8U9CoCb1K yI5ud33tciU7bwXXwQGL8V1Yzc757HU= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=V274faEo; spf=pass (imf11.hostedemail.com: domain of shakeel.butt@linux.dev designates 95.215.58.182 as permitted sender) smtp.mailfrom=shakeel.butt@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1741932946; a=rsa-sha256; cv=none; b=3HT/VNvZeJQdrexYY5V4gDjd/T6SlfKsrkOZiWoElptoR8y0L+sUofAlwZqnLgKp7iO+ZY +N5DHxEL2NZCcp/YKzNTmXbtDduOawLDy9uiobekp8kYpoSZWlQAIizdjcvtZq+H5ruwR0 2vRWJY8sK4jqMSHL+gx51KFHEKw+IxA= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1741932944; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=tHvct7NUO2otKVtcPkikbwH9IxeqmMsC6tyfV+hMsCI=; b=V274faEovU31wH6hmPF8Pl1ql5SCdkECGFNsM9aIg8fqkshlyZQjJkHlOiibZ5eK8EBIaF mzT2xavCrHmwrG2e71ysA2lRB0K2dCx5x92LDIJjzGPXTyyBhrFDUktB4v80nkwy47GVhp OIu/u1LFsSewxNzC4GuEWlmMp1zITI8= From: Shakeel Butt To: Andrew Morton Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Vlastimil Babka , Sebastian Andrzej Siewior , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Meta kernel team Subject: [RFC PATCH 06/10] memcg: do obj_cgroup_put inside drain_obj_stock Date: Thu, 13 Mar 2025 23:15:07 -0700 Message-ID: <20250314061511.1308152-7-shakeel.butt@linux.dev> In-Reply-To: <20250314061511.1308152-1-shakeel.butt@linux.dev> References: <20250314061511.1308152-1-shakeel.butt@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Stat-Signature: wh985qbkondrhzqq8woj6xpahtkythcn X-Rspamd-Queue-Id: E834C40004 X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1741932945-386383 X-HE-Meta: U2FsdGVkX19N+8N0Dli00bdsLr8owWaDRDskts4s73tW8GcAy/cG5eiXff/Uu22OBbmEq2ErR/dhJyKhV21l8BjKrHV9/wQ0TqPoX5n7IRakqXxLxwiYsE6XCNSEjc5D03bRHMcOgnoJM/Ylj0JHCa5imZjkqMhvn1PNqCJDUqfIdi9mZow4UHLL2SXPEftR8SsqxP/5n6FMMS+IofoCrxIprLNtsCY7sPVt82/YThJ7DUuZrDKHjCGi334RfPt4kmH1Us0WIUIV/3JVc4PihpsU9sOOW5WW8xUeC2AhSA3jqMKCrGBO855X2NoLZ8YoOnYdkNO+crVGUx33LdWtMNVOpYBUSntCyc3O0XNiN2dzex0yJYnzcA1WlsajSZjhUcMxFy68rulJcl9ZunJl3qKPKQNgxQ8eYXuK2n33XShgAs+7TF+MN+bP95/G7B3hSeRqa2IY7FedydFppOHR8i35iwmgKm6UcFaFYFKMKV6loVCyUWCCQfVX4XaHtlucWvIBMIrrsv8wJgIjrT2aXCrQZ0UnEtXo22/M1x7Vx/c3TyqT/bKII2cc+FjIz6+ZKU2t+juyZ0Ebx/iKl+vNGIUsXSrCxc/rOtsW6Uige9dd6pclTwIM1Fgan8YunNv3jqk+4MWNyYwy9YBpYPDOy/Vk+ieuBmZWot/nLdQHn2tPGfPc8RnMDYTo7/i8YEvQqlF4xvyPvsD+N4AS3GCLVVSKXFKB6Nd0Ov6TadTVua3MmE6qYg2cnuzIHYgNG7b7pdjVQFOsVlmRFErJvsgNx6oHlMWLN8wklnS996FpAST1d/ofYWkiIv/c/q6vnk13781n1JwtSikp6ndk0D5ubHL9Lf7a8HbcQMYHo0oWPuw/D+08SA17d9t8kDdMQUtFYT1Uy8NYre/PGLW1JJiJQsvDCw0/nnICgj+iQOIdP3DjD8BE/LtldYFXoUjlpDbeP5TH6ktNW48sQ5oDPXS mbNi2lsw lkoRniPAXl6INZT6qxmixiCvi61ZotqP5YIA2dj/+63JdCGzlOjg9ZIMmr6UpiorN6j3JXFY1RBzonp9G3aKR6UJJ48MojN9pm+myhvUF65LM4M0r9BDjefdzt+9tfsNG9P5aLHQNXu3KPAKDGph6ef1NOpwv0hTPW3eTltNX8RfDiKQbOOjnhyMj4zwsSha4Ryq46EObskdOzwU+Td6BEhmnug== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Previously we could not call obj_cgroup_put() inside the local lock because on the put on the last reference, the release function obj_cgroup_release() may try to re-acquire the local lock. However that chain has been broken. Now simply do obj_cgroup_put() inside drain_obj_stock() instead of returning the old objcg. Signed-off-by: Shakeel Butt --- mm/memcontrol.c | 37 +++++++++++-------------------------- 1 file changed, 11 insertions(+), 26 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 83db180455a1..3c4de384b5a0 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1778,7 +1778,7 @@ static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock) = { }; static DEFINE_MUTEX(percpu_charge_mutex); -static struct obj_cgroup *drain_obj_stock(struct memcg_stock_pcp *stock); +static void drain_obj_stock(struct memcg_stock_pcp *stock); static bool obj_stock_flush_required(struct memcg_stock_pcp *stock, struct mem_cgroup *root_memcg); @@ -1853,7 +1853,6 @@ static void drain_stock(struct memcg_stock_pcp *stock) static void drain_local_stock(struct work_struct *dummy) { struct memcg_stock_pcp *stock; - struct obj_cgroup *old = NULL; unsigned long flags; /* @@ -1864,12 +1863,11 @@ static void drain_local_stock(struct work_struct *dummy) localtry_lock_irqsave(&memcg_stock.stock_lock, flags); stock = this_cpu_ptr(&memcg_stock); - old = drain_obj_stock(stock); + drain_obj_stock(stock); drain_stock(stock); clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags); localtry_unlock_irqrestore(&memcg_stock.stock_lock, flags); - obj_cgroup_put(old); } /* Should never be called with root_mem_cgroup. */ @@ -1951,18 +1949,16 @@ void drain_all_stock(struct mem_cgroup *root_memcg) static int memcg_hotplug_cpu_dead(unsigned int cpu) { struct memcg_stock_pcp *stock; - struct obj_cgroup *old; unsigned long flags; stock = &per_cpu(memcg_stock, cpu); /* drain_obj_stock requires stock_lock */ localtry_lock_irqsave(&memcg_stock.stock_lock, flags); - old = drain_obj_stock(stock); + drain_obj_stock(stock); localtry_unlock_irqrestore(&memcg_stock.stock_lock, flags); drain_stock(stock); - obj_cgroup_put(old); return 0; } @@ -2745,24 +2741,20 @@ void __memcg_kmem_uncharge_page(struct page *page, int order) } /* Replace the stock objcg with objcg, return the old objcg */ -static struct obj_cgroup *replace_stock_objcg(struct memcg_stock_pcp *stock, - struct obj_cgroup *objcg) +static void replace_stock_objcg(struct memcg_stock_pcp *stock, + struct obj_cgroup *objcg) { - struct obj_cgroup *old = NULL; - - old = drain_obj_stock(stock); + drain_obj_stock(stock); obj_cgroup_get(objcg); stock->nr_bytes = atomic_read(&objcg->nr_charged_bytes) ? atomic_xchg(&objcg->nr_charged_bytes, 0) : 0; WRITE_ONCE(stock->cached_objcg, objcg); - return old; } static void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat, enum node_stat_item idx, int nr) { struct memcg_stock_pcp *stock; - struct obj_cgroup *old = NULL; unsigned long flags; int *bytes; @@ -2775,7 +2767,7 @@ static void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat, * changes. */ if (READ_ONCE(stock->cached_objcg) != objcg) { - old = replace_stock_objcg(stock, objcg); + replace_stock_objcg(stock, objcg); stock->cached_pgdat = pgdat; } else if (stock->cached_pgdat != pgdat) { /* Flush the existing cached vmstat data */ @@ -2816,7 +2808,6 @@ static void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat, __mod_objcg_mlstate(objcg, pgdat, idx, nr); localtry_unlock_irqrestore(&memcg_stock.stock_lock, flags); - obj_cgroup_put(old); } static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes) @@ -2838,12 +2829,12 @@ static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes) return ret; } -static struct obj_cgroup *drain_obj_stock(struct memcg_stock_pcp *stock) +static void drain_obj_stock(struct memcg_stock_pcp *stock) { struct obj_cgroup *old = READ_ONCE(stock->cached_objcg); if (!old) - return NULL; + return; if (stock->nr_bytes) { unsigned int nr_pages = stock->nr_bytes >> PAGE_SHIFT; @@ -2896,11 +2887,7 @@ static struct obj_cgroup *drain_obj_stock(struct memcg_stock_pcp *stock) } WRITE_ONCE(stock->cached_objcg, NULL); - /* - * The `old' objects needs to be released by the caller via - * obj_cgroup_put() outside of memcg_stock_pcp::stock_lock. - */ - return old; + obj_cgroup_put(old); } static bool obj_stock_flush_required(struct memcg_stock_pcp *stock, @@ -2922,7 +2909,6 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes, bool allow_uncharge) { struct memcg_stock_pcp *stock; - struct obj_cgroup *old = NULL; unsigned long flags; unsigned int nr_pages = 0; @@ -2930,7 +2916,7 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes, stock = this_cpu_ptr(&memcg_stock); if (READ_ONCE(stock->cached_objcg) != objcg) { /* reset if necessary */ - old = replace_stock_objcg(stock, objcg); + replace_stock_objcg(stock, objcg); allow_uncharge = true; /* Allow uncharge when objcg changes */ } stock->nr_bytes += nr_bytes; @@ -2941,7 +2927,6 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes, } localtry_unlock_irqrestore(&memcg_stock.stock_lock, flags); - obj_cgroup_put(old); if (nr_pages) obj_cgroup_uncharge_pages(objcg, nr_pages);