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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 21/30] mm/vma: add and use vma_[add/sub]_pgoff() Message-ID: References: <794044881e454fd8ac13e59d5ff5fc86fca08b03.1782735110.git.ljs@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 3729C1C0009 X-Stat-Signature: k54fbks8ye7udf1jdz6g371bmsxngooa X-HE-Tag: 1783419786-127418 X-HE-Meta: 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 +g/i1GHC vnlhEx0ubuc55HWzZU2YU6dWcEZMZfPH7pJtxE/ZRYsb4rrhu4DV8a4Gqe2MUaCdq9bnXlohMlawh+4KYQTrG3l2zBj7/iGEmMaNWguPB5nF98KBxPZFf1ssHimXkzkUdXO+9WisKPSiji1W9lWDe1p0a0k/oGkreEH8yoaiGeJTdNSQNsAHVlBeNkerPq0EaRCJ28uc0gkAeK3pBH42Abr8u4IhVzp9BYmcjMIsn6f1m0oVtSw2McttQ6lmUUDRThmjJgC8YYogE5pkHWNtYmuDGIG4D+7gVAOqkSjLZxo8NqkH1LSaNPhdPpzEmLwvTPb9YyKf7gbOSVhh8pI+bj/gfZZDukkl6yfv3azNcSOh2vem6wijLhO5xZAvd0kghG3YeUF/tAtQf7rUvKwfNELiOJw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Jul 02, 2026 at 12:20:10PM +0100, Pedro Falcato wrote: > On Mon, Jun 29, 2026 at 01:23:32PM +0100, Lorenzo Stoakes wrote: > > Add helpers for adding or subtracting to a VMA's page offset, exposed > > internally for VMA users within mm in mm/vma.h. > > > > This is to lay the foundations for tracking anonymous page offset for > > MAP_PRIVATE file-backed mappings, where adding and subtracting from this > > value must be reflected in both the file and anonymous offsets. > > > > These are used on VMA split and downward stack expansion. > > > > No functional change intended. > > > > Signed-off-by: Lorenzo Stoakes > > --- > > mm/nommu.c | 6 ++++-- > > mm/vma.c | 6 +++--- > > mm/vma.h | 12 ++++++++++++ > > tools/testing/vma/include/dup.h | 13 ++++++++++++- > > 4 files changed, 31 insertions(+), 6 deletions(-) > > > > diff --git a/mm/nommu.c b/mm/nommu.c > > index 7333d855e974..c7fafcd87c14 100644 > > --- a/mm/nommu.c > > +++ b/mm/nommu.c > > @@ -41,6 +41,7 @@ > > #include > > #include > > #include "internal.h" > > +#include "vma.h" > > > > unsigned long highest_memmap_pfn; > > int heap_stack_gap = 0; > > @@ -1338,7 +1339,8 @@ static int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma, > > region->vm_top = region->vm_end = new->vm_end = addr; > > } else { > > region->vm_start = new->vm_start = addr; > > - region->vm_pgoff = new->vm_pgoff += npages; > > + vma_add_pgoff(new, npages); > > + region->vm_pgoff = vma_start_pgoff(new); > > } > > > > vma_iter_config(vmi, new->vm_start, new->vm_end); > > @@ -1355,7 +1357,7 @@ static int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma, > > delete_nommu_region(vma->vm_region); > > if (new_below) { > > vma->vm_region->vm_start = vma->vm_start = addr; > > - vma->vm_pgoff += npages; > > + vma_add_pgoff(vma, npages); > > vma->vm_region->vm_pgoff = vma_start_pgoff(vma); > > } else { > > vma->vm_region->vm_end = vma->vm_end = addr; > > diff --git a/mm/vma.c b/mm/vma.c > > index 185d07397ca6..cb7222e20c93 100644 > > --- a/mm/vma.c > > +++ b/mm/vma.c > > @@ -517,7 +517,7 @@ __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma, > > new->vm_end = addr; > > } else { > > new->vm_start = addr; > > - new->vm_pgoff += linear_page_delta(vma, addr); > > + vma_add_pgoff(new, linear_page_delta(vma, addr)); > > } > > > > err = -ENOMEM; > > @@ -556,7 +556,7 @@ __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma, > > > > if (new_below) { > > vma->vm_start = addr; > > - vma->vm_pgoff += (addr - new->vm_start) >> PAGE_SHIFT; > > + vma_add_pgoff(vma, (addr - new->vm_start) >> PAGE_SHIFT); > > } else { > > vma->vm_end = addr; > > } > > @@ -3305,7 +3305,7 @@ int expand_downwards(struct vm_area_struct *vma, unsigned long address) > > vm_stat_account(mm, vma->vm_flags, grow); > > anon_vma_interval_tree_pre_update_vma(vma); > > vma->vm_start = address; > > - vma->vm_pgoff -= grow; > > + vma_sub_pgoff(vma, grow); > > /* Overwrite old entry in mtree. */ > > vma_iter_store_overwrite(&vmi, vma); > > anon_vma_interval_tree_post_update_vma(vma); > > diff --git a/mm/vma.h b/mm/vma.h > > index 2342516ce00e..47fe35e5307e 100644 > > --- a/mm/vma.h > > +++ b/mm/vma.h > > @@ -247,6 +247,18 @@ static inline pgoff_t vmg_end_pgoff(const struct vma_merge_struct *vmg) > > return vmg_start_pgoff(vmg) + vmg_pages(vmg); > > } > > > > +static inline void vma_add_pgoff(struct vm_area_struct *vma, pgoff_t delta) > > +{ > > + vma_assert_can_modify(vma); > > + vma->vm_pgoff += delta; > > +} > > + > > +static inline void vma_sub_pgoff(struct vm_area_struct *vma, pgoff_t delta) > > +{ > > + vma_assert_can_modify(vma); > > + vma->vm_pgoff -= delta; > > +} > > + > > #define VMG_STATE(name, mm_, vmi_, start_, end_, vma_flags_, pgoff_) \ > > struct vma_merge_struct name = { \ > > .mm = mm_, \ > > diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/dup.h > > index 7ed165c8d9bc..41fea90a344d 100644 > > --- a/tools/testing/vma/include/dup.h > > +++ b/tools/testing/vma/include/dup.h > > @@ -1163,6 +1163,11 @@ static inline struct vm_area_struct *vma_next(struct vma_iterator *vmi) > > return mas_find(&vmi->mas, ULONG_MAX); > > } > > > > +static inline bool vma_is_attached(struct vm_area_struct *vma) > > +{ > > + return refcount_read(&vma->vm_refcnt); > > +} > > + > > /* > > * WARNING: to avoid racing with vma_mark_attached()/vma_mark_detached(), these > > * assertions should be made either under mmap_write_lock or when the object > > @@ -1170,7 +1175,13 @@ static inline struct vm_area_struct *vma_next(struct vma_iterator *vmi) > > */ > > static inline void vma_assert_attached(struct vm_area_struct *vma) > > { > > - WARN_ON_ONCE(!refcount_read(&vma->vm_refcnt)); > > + WARN_ON_ONCE(!vma_is_attached(vma)); > > +} > > + > > +static inline void vma_assert_can_modify(struct vm_area_struct *vma) > > +{ > > + if (vma_is_attached(vma)) > > + vma_assert_write_locked(vma); > > } > > These hunks in dup.h look lost. Should perhaps be on the previous patch > (adding the helpers). Yeah, it's because the VMA code starts actually using them in a way that otherwise breaks the tests at this point, but you're right, functionally it'd be nicer to add them at the point they're introduced. Will fix that up on respin! > > Anyway, Obviously Correct(tm). > > Reviewed-by: Pedro Falcato Thanks! > > -- > Pedro Cheers, Lorenzo