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 186DCE63F11 for ; Sun, 15 Feb 2026 20:11:08 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0A3C36B00A8; Sun, 15 Feb 2026 15:11:08 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 0513B6B00A9; Sun, 15 Feb 2026 15:11:07 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EC98C6B00AB; Sun, 15 Feb 2026 15:11:07 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id CB3676B00A8 for ; Sun, 15 Feb 2026 15:11:07 -0500 (EST) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 0B92F13C009 for ; Sun, 15 Feb 2026 17:45:18 +0000 (UTC) X-FDA: 84447417516.02.E6AC0B0 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf29.hostedemail.com (Postfix) with ESMTP id 4B053120012 for ; Sun, 15 Feb 2026 17:45:16 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=BG+JR1Dy; spf=pass (imf29.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1771177516; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=FhUEBdNMB+2oojblmVUteZDfEmdnPWnoqtn3OWIqyYM=; b=NuYojmZy4x6P9TymSn/jZ+v7LgKCmepYOSvG5V6LbY76eyoKIH62Y5YS3qD6E5MlzPWCe+ xUSkYWzRSlsfDwH0tdil3sYeQ+MuFTsjevzqgFMT4y+wU4g7wvYOtXCsNq9ePSVdRPSdUU CJVb30kQOGfDIptXJGZhunfsL9l5ySA= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1771177516; a=rsa-sha256; cv=none; b=o+2wYog/+21C+kAYOhZX4e8QJ+/JWDaZssYQv431q888HmHFCTq47Em7OZpm71nStgvt/G t5jBA4S3iYAQCCW0/eeVxLnCSAskKeEVGDhmAJksrDTQwn9QKPCAQ+AeV6PYLnsKfwKKC4 rZykldvH8pjgtX1fuQmbAW4xjTNyUD8= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=BG+JR1Dy; spf=pass (imf29.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 5A34D43660; Sun, 15 Feb 2026 17:45:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7335BC4CEF7; Sun, 15 Feb 2026 17:45:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771177515; bh=8+vsibyilKDKEZUlnlJrlviFTSx+hiIe6MQ75WXS7Rk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=BG+JR1Dyi5VqlUUTMQf5o+IiWg/T2f3iM50oVhUC5iCYomQGcsnmguUIxywRlub2p egB1quc0DK4f9M6/YLQTkMXWoMuBxZURAiXTZJqY4zFmhsg0k951pvj6wr8eH9F8wU AM5JBmF6GY00arsIj/PxFJgo7GvSr9q2JubVLEHPAeo7A8BtVruoSMUZ7BFkzRhuog Ex2bquQwk1LKEv9t0ST+8RVfYCe9ouxUlpG0FOs2qowxphlyDvx+mfSzVM+KgqcIxV mUUtlI+5N1rCjkyk4hN+zdv8vjrFDLhhO5ln9E5kcqJad0eDxPxQ4gCLobLT56qZZr ODkw7iWdblQ1w== Date: Sun, 15 Feb 2026 19:45:04 +0200 From: Mike Rapoport To: Peter Xu Cc: linux-mm@kvack.org, Andrea Arcangeli , Andrew Morton , Axel Rasmussen , Baolin Wang , David Hildenbrand , Hugh Dickins , James Houghton , "Liam R. Howlett" , Lorenzo Stoakes , Michal Hocko , Muchun Song , Nikita Kalyazin , Oscar Salvador , Paolo Bonzini , Sean Christopherson , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH RFC 10/17] shmem, userfaultfd: implement shmem uffd operations using vm_uffd_ops Message-ID: References: <20260127192936.1250096-1-rppt@kernel.org> <20260127192936.1250096-11-rppt@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 4B053120012 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: htcqwxm38cin36i4cqjcqwewj7ccz1xj X-HE-Tag: 1771177516-947763 X-HE-Meta: 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 dsXrUwIU 5KWcykWzDbamVFbLl0KbCvwyrAeruN255P9LHkdb5Bs4hZvTEODEIzbO8Vx4qFs6SorIsJM4s2zgpyutWs7pVovDvEOUuzjYTeKMMNYvXkY9uPZJB/U8y5qiox9s8wOcKRJjsvXfvtKpBUllLYXoHa0hZ2feDC2nN3tO1lUjPPU8u+Q+snEKJGAByxizG3PU5L52G8AuprWuLlHiqIspHQt8O36kUPXQMjbrNY5gDbdxuoyxFSoUyctAOaiuzjvnjxdb136DDKUQYMeKg1SJy8zb2QF6Ak2KVH1bgjbIBMqv49rc= 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: On Wed, Feb 11, 2026 at 03:00:58PM -0500, Peter Xu wrote: > On Sun, Feb 08, 2026 at 12:35:43PM +0200, Mike Rapoport wrote: > > > > +static void shmem_mfill_filemap_remove(struct folio *folio, > > > > + struct vm_area_struct *vma) > > > > +{ > > > > + struct inode *inode = file_inode(vma->vm_file); > > > > + > > > > + filemap_remove_folio(folio); > > > > + shmem_recalc_inode(inode, 0, 0); > > > > folio_unlock(folio); > > > > - folio_put(folio); > > > > -out_unacct_blocks: > > > > - shmem_inode_unacct_blocks(inode, 1); > > > > > > This looks wrong, or maybe I miss somewhere we did the unacct_blocks()? > > > > This is handled by shmem_recalc_inode(inode, 0, 0). > > IIUC shmem_recalc_inode() only does the fixup of shmem_inode_info over > possiblly changing inode->i_mapping->nrpages. It's not for reverting the > accounting in the failure paths here. > > OTOH, we still need to maintain accounting for the rest things with > correctly invoke shmem_inode_unacct_blocks(). One thing we can try is > testing this series against either shmem quota support (since 2023, IIUC > it's relevant to "quota" mount option), or max_blocks accountings (IIUC, > "size" mount option), etc. Any of those should reflect a difference if my > understanding is correct. > > So IIUC we still need the unacct_blocks(), please kindly help double check. I followed shmem_get_folio_gfp() error handling, and unless I missed something we should have the same sequence with uffd. In shmem_mfill_filemap_add() we increment both i_mapping->nrpages and info->alloced in shmem_add_to_page_cache() and shmem_recalc_inode(inode, 1, 0) respectively. Then in shmem_filemap_remove() the call to filemap_remove_folio() decrements i_mapping->nrpages and shmem_recalc_inode(inode, 0, 0) will see freed=1 and will call shmem_inode_unacct_blocks(). > Thanks, > > -- > Peter Xu > -- Sincerely yours, Mike.