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Tue, 30 Jun 2026 16:36:19 +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 GZUpNYPwQ2qifgAAD6G6ig (envelope-from ); Tue, 30 Jun 2026 16:36:19 +0000 Date: Tue, 30 Jun 2026 17:36:18 +0100 From: Pedro Falcato To: Lorenzo Stoakes Cc: Andrew Morton , Russell King , Dinh Nguyen , Simon Schuster , "James E . J . Bottomley" , Helge Deller , Jarkko Sakkinen , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Ian Abbott , H Hartley Sweeten , Lucas Stach , David Airlie , Simona Vetter , Patrik Jakobsson , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Rob Clark , Dmitry Baryshkov , Tomi Valkeinen , Thierry Reding , Mikko Perttunen , Jonathan Hunter , Christian Koenig , Huang Rui , Ankit Agrawal , Alex Williamson , Alexander Viro , Christian Brauner , Dan Williams , Muchun Song , Oscar Salvador , David Hildenbrand , Suren Baghdasaryan , "Liam R . Howlett" , Matthew Wilcox , Marek Szyprowski , Peter Zijlstra , Arnaldo Carvalho de Melo , Namhyung Kim , Masami Hiramatsu , Oleg Nesterov , Steven Rostedt , SeongJae Park , Miaohe Lin , Hugh Dickins , Mike Rapoport , Kees Cook , Paolo Bonzini , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-parisc@vger.kernel.org, linux-sgx@vger.kernel.org, etnaviv@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org, linux-tegra@vger.kernel.org, kvm@vger.kernel.org, linux-fsdevel@vger.kernel.org, nvdimm@lists.linux.dev, linux-mm@kvack.org, iommu@lists.linux.dev, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org, kasan-dev@googlegroups.com, damon@lists.linux.dev, Rik van Riel , Harry Yoo , Jann Horn Subject: Re: [PATCH 12/30] mm/vma: clean up anon_vma_compatible() Message-ID: References: <5a7a07bd2a774989849b0fea84f758059ed914df.1782735110.git.ljs@kernel.org> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5a7a07bd2a774989849b0fea84f758059ed914df.1782735110.git.ljs@kernel.org> X-Spam-Flag: NO X-Rspamd-Action: no action X-Spam-Level: X-Spamd-Result: default: False [-3.01 / 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]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; FREEMAIL_CC(0.00)[linux-foundation.org,armlinux.org.uk,kernel.org,siemens-energy.com,hansenpartnership.com,gmx.de,redhat.com,alien8.de,linux.intel.com,mev.co.uk,visionengravers.com,pengutronix.de,gmail.com,ffwll.ch,suse.de,oss.qualcomm.com,ideasonboard.com,nvidia.com,amd.com,shazbot.org,zeniv.linux.org.uk,linux.dev,google.com,infradead.org,samsung.com,goodmis.org,huawei.com,vger.kernel.org,lists.infradead.org,lists.freedesktop.org,lists.linux.dev,kvack.org,googlegroups.com,surriel.com]; FROM_HAS_DN(0.00)[]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; MIME_TRACE(0.00)[0:+]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; ARC_NA(0.00)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; RCVD_TLS_ALL(0.00)[]; DKIM_TRACE(0.00)[suse.de:+]; MISSING_XM_UA(0.00)[]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; TO_DN_SOME(0.00)[]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:104:10:150:64:97:from,2a07:de40:b281:106:10:150:64:167:received]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; RCPT_COUNT_GT_50(0.00)[75]; RCVD_VIA_SMTP_AUTH(0.00)[]; TAGGED_RCPT(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[pedro-suse.lan:mid,imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns,suse.de:email,suse.de:dkim] X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Queue-Id: 9485D75953 X-Spam-Score: -3.01 On Mon, Jun 29, 2026 at 01:23:23PM +0100, Lorenzo Stoakes wrote: > Break up the existing very large conditional, add comments and use > vma_[start/end]_pgoff() to make clearer what we're doing here. > > No functional change intended. > > Signed-off-by: Lorenzo Stoakes > --- > mm/vma.c | 21 ++++++++++++++++----- > 1 file changed, 16 insertions(+), 5 deletions(-) > > diff --git a/mm/vma.c b/mm/vma.c > index b60375c6c5c3..6296acecf3b7 100644 > --- a/mm/vma.c > +++ b/mm/vma.c > @@ -1967,14 +1967,25 @@ static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct * > { > vma_flags_t diff = vma_flags_diff_pair(&a->flags, &b->flags); > > + /* Ignore flags that mprotect() can change. */ > vma_flags_clear_mask(&diff, VMA_ACCESS_FLAGS); > + /* Ignore flags that do not impact merging. */ > vma_flags_clear_mask(&diff, VMA_IGNORE_MERGE_FLAGS); > > - return a->vm_end == b->vm_start && > - mpol_equal(vma_policy(a), vma_policy(b)) && > - a->vm_file == b->vm_file && > - vma_flags_empty(&diff) && > - b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT); > + /* Must be adjacent. */ > + if (a->vm_end != b->vm_start) > + return false; > + /* Must have matching policy. */ > + if (!mpol_equal(vma_policy(a), vma_policy(b))) > + return false; > + /* Must both be anon or map the same file (MAP_PRIVATE case). */ > + if (a->vm_file != b->vm_file) > + return false; > + /* Flags must be equivalent modulo mprotect(). */ > + if (!vma_flags_empty(&diff)) > + return false; > + /* Page offset must align. */ > + return vma_end_pgoff(a) == vma_start_pgoff(b); Very nice. Reviewed-by: Pedro Falcato -- Pedro