From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.223.130]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4C97B2EE617 for ; Fri, 10 Oct 2025 12:48:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.135.223.130 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760100531; cv=none; b=t8WcwmXevxiL/8fOao6CrDwhcDd5An6MvQfd4nsHy1w4vO5uOk7JyLW5yYkW3GIl57re1tfw+Z+f1NePc/8UlJdzauR48cG6dqEFwF5H0VORmYZlSq3Y7Balvc5Hi2blNKV5byAwz5YWLDw2JklH18pa5F8KOvbpSwF5XfbaUT8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760100531; c=relaxed/simple; bh=N1+yDWTcvP8w1JxXGMNph1gBa9q47mbzc2toHVbSUI4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=csde7QqFjtmIRvhxcif73zEaepIooAb1DwByiNwAhO4SkBYYLPjWKG6QJlKymOqnp72gCHuLsHyFqw9nDZtsvUj9yGfYzreeO10r+Sc2tEalfoavCYx0+Hjn6MN7amuq7PcnLKOLg+OHbWUHb8IjBokg7FqIPjK0ymzwKwNoecA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz; spf=pass smtp.mailfrom=suse.cz; dkim=pass (1024-bit key) header.d=suse.cz header.i=@suse.cz header.b=Cw+mD3lQ; dkim=permerror (0-bit key) header.d=suse.cz header.i=@suse.cz header.b=X7LVzkzU; dkim=pass (1024-bit key) header.d=suse.cz header.i=@suse.cz header.b=Cw+mD3lQ; dkim=permerror (0-bit key) header.d=suse.cz header.i=@suse.cz header.b=X7LVzkzU; arc=none smtp.client-ip=195.135.223.130 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.cz Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=suse.cz header.i=@suse.cz header.b="Cw+mD3lQ"; dkim=permerror (0-bit key) header.d=suse.cz header.i=@suse.cz header.b="X7LVzkzU"; dkim=pass (1024-bit key) header.d=suse.cz header.i=@suse.cz header.b="Cw+mD3lQ"; dkim=permerror (0-bit key) header.d=suse.cz header.i=@suse.cz header.b="X7LVzkzU" Received: from imap1.dmz-prg2.suse.org (unknown [10.150.64.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 5C14C21286; Fri, 10 Oct 2025 12:48:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1760100526; h=from:from:reply-to: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:in-reply-to:references:references:autocrypt:autocrypt; bh=2DWhJpAvXNt4nGU+zHS2kg0wKNnrOVaGhcDqNB9SnGw=; b=Cw+mD3lQSfjtcU67FOtqzm5CefE22ZmxqJmO4CNuHknEKRL9PVnsL2xXPHc8z6CDU/imkF St1Dzjoxn+nh+nHIbVoWbeTCxVNszJI5Sm6px/YOffWq6gvBgH3YYbMFgk1sxukB8uBkqU rw/8DQwIs482W5EBay7Wd5oGn3Q/OWM= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1760100526; h=from:from:reply-to: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:in-reply-to:references:references:autocrypt:autocrypt; bh=2DWhJpAvXNt4nGU+zHS2kg0wKNnrOVaGhcDqNB9SnGw=; b=X7LVzkzUlRR5FaQmTI+inzg/5S0RNFQviraVnjRA/Vb436LZfNyajmiwNEofTAeeK4OxII zLpVFDD9RgjpRGCQ== Authentication-Results: smtp-out1.suse.de; none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1760100526; h=from:from:reply-to: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:in-reply-to:references:references:autocrypt:autocrypt; bh=2DWhJpAvXNt4nGU+zHS2kg0wKNnrOVaGhcDqNB9SnGw=; b=Cw+mD3lQSfjtcU67FOtqzm5CefE22ZmxqJmO4CNuHknEKRL9PVnsL2xXPHc8z6CDU/imkF St1Dzjoxn+nh+nHIbVoWbeTCxVNszJI5Sm6px/YOffWq6gvBgH3YYbMFgk1sxukB8uBkqU rw/8DQwIs482W5EBay7Wd5oGn3Q/OWM= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1760100526; h=from:from:reply-to: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:in-reply-to:references:references:autocrypt:autocrypt; bh=2DWhJpAvXNt4nGU+zHS2kg0wKNnrOVaGhcDqNB9SnGw=; b=X7LVzkzUlRR5FaQmTI+inzg/5S0RNFQviraVnjRA/Vb436LZfNyajmiwNEofTAeeK4OxII zLpVFDD9RgjpRGCQ== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 428AE13A40; Fri, 10 Oct 2025 12:48:46 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id XkbGD64A6WgeNwAAD6G6ig (envelope-from ); Fri, 10 Oct 2025 12:48:46 +0000 Message-ID: <63bbcf0d-5a02-4eba-8fc1-680eeb4e09cb@suse.cz> Date: Fri, 10 Oct 2025 14:48:45 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/3] mm/page_alloc: Batch page freeing in decay_pcp_high Content-Language: en-US To: Joshua Hahn , Andrew Morton Cc: Chris Mason , Kiryl Shutsemau , Brendan Jackman , Johannes Weiner , Michal Hocko , Suren Baghdasaryan , Zi Yan , linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel-team@meta.com References: <20251002204636.4016712-1-joshua.hahnjy@gmail.com> <20251002204636.4016712-3-joshua.hahnjy@gmail.com> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJnyBr8BQka0IFQAAoJECJPp+fMgqZkqmMQ AIbGN95ptUMUvo6aAdhxaOCHXp1DfIBuIOK/zpx8ylY4pOwu3GRe4dQ8u4XS9gaZ96Gj4bC+ jwWcSmn+TjtKW3rH1dRKopvC07tSJIGGVyw7ieV/5cbFffA8NL0ILowzVg8w1ipnz1VTkWDr 2zcfslxJsJ6vhXw5/npcY0ldeC1E8f6UUoa4eyoskd70vO0wOAoGd02ZkJoox3F5ODM0kjHu Y97VLOa3GG66lh+ZEelVZEujHfKceCw9G3PMvEzyLFbXvSOigZQMdKzQ8D/OChwqig8wFBmV QCPS4yDdmZP3oeDHRjJ9jvMUKoYODiNKsl2F+xXwyRM2qoKRqFlhCn4usVd1+wmv9iLV8nPs 2Db1ZIa49fJet3Sk3PN4bV1rAPuWvtbuTBN39Q/6MgkLTYHb84HyFKw14Rqe5YorrBLbF3rl M51Dpf6Egu1yTJDHCTEwePWug4XI11FT8lK0LNnHNpbhTCYRjX73iWOnFraJNcURld1jL1nV r/LRD+/e2gNtSTPK0Qkon6HcOBZnxRoqtazTU6YQRmGlT0v+rukj/cn5sToYibWLn+RoV1CE Qj6tApOiHBkpEsCzHGu+iDQ1WT0Idtdynst738f/uCeCMkdRu4WMZjteQaqvARFwCy3P/jpK uvzMtves5HvZw33ZwOtMCgbpce00DaET4y/UzsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZ8gcVAUJFhTonwAKCRAiT6fnzIKmZLY8D/9uo3Ut9yi2YCuASWxr7QQZ lJCViArjymbxYB5NdOeC50/0gnhK4pgdHlE2MdwF6o34x7TPFGpjNFvycZqccSQPJ/gibwNA zx3q9vJT4Vw+YbiyS53iSBLXMweeVV1Jd9IjAoL+EqB0cbxoFXvnjkvP1foiiF5r73jCd4PR rD+GoX5BZ7AZmFYmuJYBm28STM2NA6LhT0X+2su16f/HtummENKcMwom0hNu3MBNPUOrujtW khQrWcJNAAsy4yMoJ2Lw51T/5X5Hc7jQ9da9fyqu+phqlVtn70qpPvgWy4HRhr25fCAEXZDp xG4RNmTm+pqorHOqhBkI7wA7P/nyPo7ZEc3L+ZkQ37u0nlOyrjbNUniPGxPxv1imVq8IyycG AN5FaFxtiELK22gvudghLJaDiRBhn8/AhXc642/Z/yIpizE2xG4KU4AXzb6C+o7LX/WmmsWP Ly6jamSg6tvrdo4/e87lUedEqCtrp2o1xpn5zongf6cQkaLZKQcBQnPmgHO5OG8+50u88D9I rywqgzTUhHFKKF6/9L/lYtrNcHU8Z6Y4Ju/MLUiNYkmtrGIMnkjKCiRqlRrZE/v5YFHbayRD dJKXobXTtCBYpLJM4ZYRpGZXne/FAtWNe4KbNJJqxMvrTOrnIatPj8NhBVI0RSJRsbilh6TE m6M14QORSWTLRg== In-Reply-To: <20251002204636.4016712-3-joshua.hahnjy@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spamd-Result: default: False [-2.80 / 50.00]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; TAGGED_RCPT(0.00)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; MIME_TRACE(0.00)[0:+]; RCPT_COUNT_TWELVE(0.00)[12]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; FREEMAIL_TO(0.00)[gmail.com,linux-foundation.org]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_TLS_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,suse.cz:mid,suse.cz:email] X-Spam-Flag: NO X-Spam-Score: -2.80 X-Spam-Level: On 10/2/25 22:46, Joshua Hahn wrote: > It is possible for pcp->count - pcp->high to exceed pcp->batch by a lot. > When this happens, we should perform batching to ensure that > free_pcppages_bulk isn't called with too many pages to free at once and > starve out other threads that need the pcp lock. ... or the zone lock. > Since we are still only freeing the difference between the initial > pcp->count and pcp->high values, there should be no change to how many > pages are freed. > > Suggested-by: Chris Mason > Suggested-by: Andrew Morton > Co-developed-by: Johannes Weiner > Signed-off-by: Joshua Hahn Reviewed-by: Vlastimil Babka > --- > mm/page_alloc.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index b9fc357d2d48..f525f197c5fd 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2559,7 +2559,7 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order, > */ > bool decay_pcp_high(struct zone *zone, struct per_cpu_pages *pcp) > { > - int high_min, to_drain, batch; > + int high_min, to_drain, to_drain_batched, batch; > bool todo = false; > > high_min = READ_ONCE(pcp->high_min); > @@ -2577,11 +2577,14 @@ bool decay_pcp_high(struct zone *zone, struct per_cpu_pages *pcp) > } > > to_drain = pcp->count - pcp->high; > - if (to_drain > 0) { > + while (to_drain > 0) { > + to_drain_batched = min(to_drain, batch); > spin_lock(&pcp->lock); > - free_pcppages_bulk(zone, to_drain, pcp, 0); > + free_pcppages_bulk(zone, to_drain_batched, pcp, 0); > spin_unlock(&pcp->lock); > todo = true; > + > + to_drain -= to_drain_batched; > } > > return todo;