From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=195.135.223.131 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794489180; b=UOyGbavhGuNv/xp4KSV3x7n5aSzK09Ir19UP9oVETo7sNFR7nI30m3jl+SHyUMEeOOgz nmtHGlSzWwJ7QjOIkfThS8sCyRvV/3ELAQuNoJH5jju7J3pN6jxDm19htLfYfLPiGYh/4 vE0YDkMRsRYKN4J7jc1Yn0Sc+NrCQdZe0C1wVS3wVk6h6UTBKZMXWWseAQCGw1qsFEOrr NhdPizCwZRgt0XUA66tos83G6QlqkCI6AgoN46rbTZBqNhH8aOpSTkugkE6B2h3EOqWOt GLD1w4//PFaGbQrrSxOA2AG2C77reIjGv3G60uGFqHFFz7nq0hQVr8iU76i9dgFCHiA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794489180; h=DMARC-Filter:Received:DKIM-Signature:DKIM-Signature:DKIM-Signature: DKIM-Signature:Received:Received:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition:In-Reply-To: X-Spam-Flag:X-Spam-Level:X-Spamd-Result:X-Spam-Score; bh=OHN1jM98e/rDidDGGpuhhKAQmbd/D3xE71tgIR8sZI0=; b=Kj+6JNPGevjVi2wpJsag3yY/tBbqcW3ftVe3Gs4yeFv7Oc8hUR6FHM7V6il7L7MF+3of bR/9NHmsJGQVNdeoslHa0eQ1i3f3xL0tReIySYtdKb70jU+ybAYXXKlhav6QS0OTnSqeM ZAZIWZ5EvT1oCVMYQtuRM0Vll/OIdcn6LDH0MI05jZirLAAviavWU9Z2Non1/f5PAfHQH LAlZo0hk4OTb2nz0UGUlsn2oOFwTSXSXkLY2iwCYEO1hzlY7aFQs2j82bBg14TrMZYyRh UEBZ22BtzlKzMSj4aq+xAHOIqW8CqJBZn5Gs2qa1BBl4WVGQ9WWkQ8nO61JI/UFg+1g== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=suse.de; spf=pass smtp.mailfrom=suse.de; dkim=pass header.d=suse.de header.i=@suse.de header.a=rsa-sha256 header.s=susede2_rsa header.b=rSVlAVBA; dkim=pass header.d=suse.de header.i=@suse.de header.a=ed25519-sha256 header.s=susede2_ed25519 header.b="K/0F5ksR"; dkim=pass header.d=suse.de header.i=@suse.de header.a=rsa-sha256 header.s=susede2_rsa header.b=eCAG9TQz; dkim=neutral header.d=suse.de header.i=@suse.de header.a=ed25519-sha256 header.s=susede2_ed25519 header.b=+Ip1OpXF; arc=none smtp.remote-ip=195.135.223.131 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.223.131]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B5A23606A31C; Thu, 12 Nov 2026 13:12:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org B5A23606A31C Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=suse.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.a=rsa-sha256 header.s=susede2_rsa header.b=rSVlAVBA; dkim=pass header.d=suse.de header.i=@suse.de header.a=ed25519-sha256 header.s=susede2_ed25519 header.b=K/0F5ksR; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.a=rsa-sha256 header.s=susede2_rsa header.b=eCAG9TQz; dkim=neutral header.d=suse.de header.i=@suse.de header.a=ed25519-sha256 header.s=susede2_ed25519 header.b=+Ip1OpXF 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-out2.suse.de (Postfix) with ESMTPS id E96121F7BA; Thu, 12 Nov 2026 13:12:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1794489178; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=OHN1jM98e/rDidDGGpuhhKAQmbd/D3xE71tgIR8sZI0=; b=rSVlAVBAuFTbEKmNvga87CMsJiAzR6P2jK3iBgYEhwBBW7M/FRgIUozQfpxdflyln1UAQp nh/gLnT58Yone9jFxprqcuST6euBhfXwojj4XxZKxY2ib/aoz/ZcNwGsAiJl0dYmgVkpuJ gBoMyEljV8teWIdoq//KYCj7hBdu09E= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1794489178; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=OHN1jM98e/rDidDGGpuhhKAQmbd/D3xE71tgIR8sZI0=; b=K/0F5ksRV1fcZHji05HSZ765KfchtCSSErL2Vc/yTWA97NFYFFH1L56VKvf8XZ8/7prJlo l2ViLDN25EO0J/Cw== Authentication-Results: smtp-out2.suse.de; none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1794489177; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=OHN1jM98e/rDidDGGpuhhKAQmbd/D3xE71tgIR8sZI0=; b=eCAG9TQzbbdiUHGqQ1rrVJEmK+TN0G3+jagjuKjYTTIdr/zfnlkgnGKDrHhDB+qsmiM45I Qmg5DK+Lv5CsnkHrL42cmj3p+tWJHH5eQhYAjpj+mzYDP0xxT18QNS23th4uQzxyrgBu+3 iwu/iIfrKhdftLrAvrnzr7MufKezlbs= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1794489177; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=OHN1jM98e/rDidDGGpuhhKAQmbd/D3xE71tgIR8sZI0=; b=+Ip1OpXFy6x05CiEfWql/dw5z+HEyAEHtC4MFasKsOyOvnZvX7onaetbPN6Pdx2GKW08xv vkL63C9JoRlmD7Dg== 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 4EF8A134A0; Thu, 12 Nov 2026 13:12:54 +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 3PJECFa79WqQcgAAD6G6ig (envelope-from ); Thu, 12 Nov 2026 13:12:54 +0000 Date: Thu, 12 Nov 2026 13:12:52 +0000 From: Pedro Falcato To: "David Hildenbrand (Arm)" Cc: Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , "Matthew Wilcox (Oracle)" , Jan Kara , Andrew Morton , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Kiryl Shutsemau , Matthew Brost , Joshua Hahn , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Peter Xu , Johannes Weiner , Song Liu , Rik van Riel , Miklos Szeredi , Alexander Viro , Christian Brauner , Hugh Dickins , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Peter Zijlstra , Arnd Bergmann , Jason Gunthorpe , Kevin Tian , "Joerg Roedel (AMD)" , Robin Murphy , Steve Sistare , John Hubbard , "Jose A. Perez de Azpillaga" , Josef Bacik , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Neal Cardwell , Kuniyuki Iwashima , Linus Torvalds , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, fuse-devel@lists.linux.dev, linux-arch@vger.kernel.org, iommu@lists.linux.dev, netdev@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v3 5/9] mm/gup: limit pagecache folio refcount when grabbing references Message-ID: References: <20261110-refcount_overflow_stable-v3-0-318625d63a98@kernel.org> <20261110-refcount_overflow_stable-v3-5-318625d63a98@kernel.org> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261110-refcount_overflow_stable-v3-5-318625d63a98@kernel.org> X-Spam-Flag: NO X-Spam-Level: X-Spamd-Result: default: False [-11.80 / 50.00]; SUSE_INTERNAL_BYPASS(-9.00)[]; 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]; MISSING_XM_UA(0.00)[]; TAGGED_RCPT(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[kernel.org,infradead.org,google.com,suse.com,suse.cz,linux-foundation.org,nvidia.com,linux.alibaba.com,linux.dev,arm.com,intel.com,gmail.com,sk.com,gourry.net,redhat.com,cmpxchg.org,fb.com,surriel.com,szeredi.hu,zeniv.linux.org.uk,arndb.de,ziepe.ca,8bytes.org,oracle.com,toxicpanda.com,davemloft.net,kvack.org,vger.kernel.org,lists.linux.dev]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCPT_COUNT_GT_50(0.00)[62]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:email,imap1.dmz-prg2.suse.org:helo] X-Spam-Score: -11.80 On Tue, Nov 10, 2026 at 09:35:45PM +0100, David Hildenbrand (Arm) wrote: > Let's add a folio_ref_count_over_limit() check in fast and slow GUP > before acquiring additional references or pins. > > Keep it simple and use the check for all folio types. > > Also propagate try_grab_folio() errors when grabbing additional > references in __get_user_pages() and in memfd_pin_folios(), so hitting > the limit returns -ENOMEM instead of -EFAULT and -EINVAL, respectively. > > Keep the existing invalid-refcount warnings. > > Fixes: 800d8c63b2e9 ("shmem: add huge pages support") > Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS") > Fixes: 793917d997df ("mm/readahead: Add large folio readahead") > Cc: stable@vger.kernel.org > Reviewed-by: Jose A. Perez de Azpillaga > Signed-off-by: David Hildenbrand (Arm) Same points about funny weird inefficiency applies, in any case: Reviewed-by: Pedro Falcato -- Pedro