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Thu, 2 Jul 2026 10:37:12 +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 cEPIKVg/RmrfQQAAD6G6ig (envelope-from ); Thu, 02 Jul 2026 10:37:12 +0000 Date: Thu, 2 Jul 2026 11:37:11 +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 13/30] mm/vma: refactor vmg_adjust_set_range() for clarity Message-ID: References: Precedence: bulk X-Mailing-List: linux-sgx@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: X-Spam-Flag: NO X-Spam-Score: -2.80 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]; MISSING_XM_UA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; MIME_TRACE(0.00)[0:+]; 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)[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]; 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)[75]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:email,pedro-suse.lan:mid,imap1.dmz-prg2.suse.org:helo] X-Spam-Level: On Mon, Jun 29, 2026 at 01:23:24PM +0100, Lorenzo Stoakes wrote: > Add comments with ASCII diagrams to describe what we're doing, avoid > dubious use of PHYS_PFN(), and use vma_start_pgoff(). > > The most complicated scenario represented here is vmg->__adjust_next_start > - when this is set, vmg->[start, end] actually indicate the range to be > retained, so take special care to describe this accurately. > > No functional change intended. > > Signed-off-by: Lorenzo Stoakes > --- > mm/vma.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++---- > 1 file changed, 47 insertions(+), 4 deletions(-) > > diff --git a/mm/vma.c b/mm/vma.c > index 6296acecf3b7..1e99fe8aa6ef 100644 > --- a/mm/vma.c > +++ b/mm/vma.c > @@ -704,11 +704,54 @@ static void vmg_adjust_set_range(struct vma_merge_struct *vmg) > pgoff_t pgoff; > > if (vmg->__adjust_middle_start) { > - adjust = vmg->middle; > - pgoff = adjust->vm_pgoff + PHYS_PFN(vmg->end - adjust->vm_start); > + /* > + * vmg->start vmg->end > + * | | > + * v merge v > + * <-------------> > + * delta > + * <------> > + * |------|----------------| > + * | prev | middle | > + * |------|----------------| > + * ^ > + * | > + * middle->vm_start > + */ > + struct vm_area_struct *middle = vmg->middle; FWIW this can be simplified to adjust = middle; const unsigned long delta = vmg->end - adjust->vm_start; But I guess you're looking for explicitness here? > + const unsigned long delta = vmg->end - middle->vm_start; > + > + pgoff = vma_start_pgoff(middle) + (delta >> PAGE_SHIFT); > + adjust = middle; > } else if (vmg->__adjust_next_start) { > - adjust = vmg->next; > - pgoff = adjust->vm_pgoff - PHYS_PFN(adjust->vm_start - vmg->end); > + /* > + * Originally: > + * > + * vmg->start vmg->end > + * | | > + * v merge v > + * <------------> > + * . . > + * merge_existing_range() updates to: > + * . . > + * vmg->start vmg->end . > + * | | . > + * v retain v . > + * <----------> . > + * delta . > + * <-----> . > + * |----------------|------| > + * | middle | next | > + * |----------------|------| > + * ^ > + * | > + * next->vm_start > + */ > + struct vm_area_struct *next = vmg->next; > + const unsigned long delta = next->vm_start - vmg->end; > + > + pgoff = vma_start_pgoff(next) - (delta >> PAGE_SHIFT); > + adjust = next; > } else { > return; > } Reviewed-by: Pedro Falcato -- Pedro