From 51943a18ad4bd6ff8baea2da7b8cce2f86f1a959 Mon Sep 17 00:00:00 2001 From: "Lorenzo Stoakes (ARM)" Date: Thu, 13 Aug 2026 18:32:19 +0100 Subject: mm: provide vma_[flags_]is_cow_mapping() and remove is_cow_mapping() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit All remaining callers of is_cow_mapping() are invoking it in the form of is_cow_mapping(vma->vm_flags) or an indirected version of this. Therefore, provide a helper - vma_is_cow_mapping() to directly test the VMA. Additionally provide a new helper vma_flags_is_cow_mapping() which performs the check using the new vma_flags_t type, and share this logic between vma_is_cow_mapping() and vma_desc_is_cow_mapping(). With these changes, no callers of is_cow_mapping() remain, so remove it. Also update the userland VMA tests to reflect the change. No functional change intended. [akpm@linux-foundation.org: fix kerneldoc comment typo, per Lorenzo] Link: https://lore.kernel.org/aob1goSSPH6sTN9y@gremlin Link: https://lore.kernel.org/20260813-b4-scalable-cow-virt-pgoff-v5-2-c21581c0c3c8@kernel.org Signed-off-by: Lorenzo Stoakes (ARM) Acked-by: David Hildenbrand (Arm) Cc: Adrian Hunter Cc: Alexander Deucher Cc: Alexander Gordeev Cc: Alexander Shishkin Cc: Alistair Popple Cc: Arnaldo Carvalho de Melo Cc: Arnd Bergmann Cc: Baolin Wang Cc: Baoquan He Cc: Barry Song Cc: Boris Brezillon Cc: Byungchul Park Cc: Chengming Zhou Cc: Chris Li Cc: Christan König Cc: Christian Borntraeger Cc: Claudio Imbrenda Cc: Dave Airlie Cc: Dev Jain Cc: Gerald Schaefer Cc: Greg Kroah-Hartman Cc: Gregory Price (Meta) Cc: Harry Yoo Cc: Heiko Carstens Cc: Huang Ray Cc: "Huang, Ying" Cc: Ian Rogers Cc: Ingo Molnar Cc: James Clark Cc: Jan Kara Cc: Jann Horn Cc: Janosch Frank Cc: Jason Gunthorpe Cc: Jiri Olsa Cc: John Hubbard Cc: Joshua Hahn Cc: Kairui Song Cc: Kees Cook Cc: Kemeng Shi Cc: Lance Yang Cc: Liam R. Howlett Cc: Liviu Dudau Cc: Maarten Lankhorst Cc: Marc Rutland Cc: "Masami Hiramatsu (Google)" Cc: Matthew Auld Cc: Matthew Brost Cc: Matthew Wilcox (Oracle) Cc: Maxime Ripard Cc: Miaohe Lin Cc: Michal Hocko Cc: Mike Rapoport Cc: Muchun Song Cc: Namhyung kim Cc: Naoya Horiguchi Cc: Nhat Pham Cc: Nico Pache Cc: Oleg Nesterov Cc: Oscar Salvador Cc: Pedro Falcato Cc: Peter Xu Cc: Peter Zijlstra Cc: Rakie Kim Cc: Rik van Riel Cc: Rodrigo Vivi Cc: Ryan Roberts Cc: Steven Price Cc: Suren Baghdasaryan Cc: Sven Schnelle Cc: Thomas Hellström Cc: Thomas Zimemrmann Cc: Vasily Gorbik Cc: Vlastimil Babka Cc: xu xin Cc: Zi Yan Signed-off-by: Andrew Morton --- drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 4 ++-- drivers/gpu/drm/drm_gem_shmem_helper.c | 2 +- drivers/gpu/drm/panthor/panthor_gem.c | 2 +- drivers/gpu/drm/ttm/ttm_bo_vm.c | 2 +- drivers/gpu/drm/xe/xe_device.c | 2 +- 5 files changed, 6 insertions(+), 6 deletions(-) (limited to 'drivers/gpu/drm') diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c index 6a0699746fbc..0c7309080a7a 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c @@ -377,9 +377,9 @@ static int amdgpu_gem_object_mmap(struct drm_gem_object *obj, struct vm_area_str /* Workaround for Thunk bug creating PROT_NONE,MAP_PRIVATE mappings * for debugger access to invisible VRAM. Should have used MAP_SHARED * instead. Clearing VM_MAYWRITE prevents the mapping from ever - * becoming writable and makes is_cow_mapping(vm_flags) false. + * becoming writable and makes vma_is_cow_mapping(vma) false. */ - if (is_cow_mapping(vma->vm_flags) && + if (vma_is_cow_mapping(vma) && !(vma->vm_flags & VM_ACCESS_FLAGS)) vm_flags_clear(vma, VM_MAYWRITE); diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index 06d019d51d3e..177d0e0b9334 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -753,7 +753,7 @@ int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct return ret; } - if (is_cow_mapping(vma->vm_flags)) + if (vma_is_cow_mapping(vma)) return -EINVAL; dma_resv_lock(shmem->base.resv, NULL); diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c index 770556353968..d2eec46f7abe 100644 --- a/drivers/gpu/drm/panthor/panthor_gem.c +++ b/drivers/gpu/drm/panthor/panthor_gem.c @@ -761,7 +761,7 @@ static int panthor_gem_mmap(struct drm_gem_object *obj, struct vm_area_struct *v return ret; } - if (is_cow_mapping(vma->vm_flags)) + if (vma_is_cow_mapping(vma)) return -EINVAL; if (!refcount_inc_not_zero(&bo->cmap.mmap_count)) { diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c index 88babf435ac2..872bf444b1f0 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c @@ -489,7 +489,7 @@ static const struct vm_operations_struct ttm_bo_vm_ops = { int ttm_bo_mmap_obj(struct vm_area_struct *vma, struct ttm_buffer_object *bo) { /* Enforce no COW since would have really strange behavior with it. */ - if (is_cow_mapping(vma->vm_flags)) + if (vma_is_cow_mapping(vma)) return -EINVAL; drm_gem_object_get(&bo->base); diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c index 9d119c95a569..de5fdf49d729 100644 --- a/drivers/gpu/drm/xe/xe_device.c +++ b/drivers/gpu/drm/xe/xe_device.c @@ -330,7 +330,7 @@ static int xe_pci_barrier_mmap(struct file *filp, if (vma->vm_end - vma->vm_start > SZ_4K) return -EINVAL; - if (is_cow_mapping(vma->vm_flags)) + if (vma_is_cow_mapping(vma)) return -EINVAL; if (vma->vm_flags & (VM_READ | VM_EXEC)) -- cgit From a8efc69a65fbef61bed0923c0de3425d74817c1c Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Mon, 13 Jul 2026 11:33:38 +0200 Subject: shmem: provide a shmem_write_folio wrapper Patch series "better block swap batching and a different take on swap_ops v5". This series makes use of the swap_iocb for block as well so that it doesn't do inefficient single-bio I/O, and then rebases the swap_ops from Baoquan on top of the now very different method structure. When running doing kernels builds, which is a workload that doesn't really do much THP anonymous memory it still gets 2x clustering for writeout and 1.2x for reading back swap in. The overall times do not actually change, though. This patch (of 7): Provide a wrapper for the shmem abuses in drm to prepare for swap I/O refactoring by keeping swap_iocb handling entirely contained in mm/. Link: https://lore.kernel.org/20260713093350.2154226-1-hch@lst.de Link: https://lore.kernel.org/20260713093350.2154226-2-hch@lst.de Signed-off-by: Christoph Hellwig Reviewed-by: Baoquan He Reviewed-by: Nhat Pham Reviewed-by: Baolin Wang Acked-by: Chris Li Reviewed-by: Kairui Song Cc: Kemeng Shi Cc: Barry Song Cc: Youngjun Park Signed-off-by: Andrew Morton --- drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 2 +- drivers/gpu/drm/ttm/ttm_backup.c | 2 +- include/linux/shmem_fs.h | 5 +---- mm/shmem.c | 7 ++++++- mm/swap.h | 4 ++++ 5 files changed, 13 insertions(+), 7 deletions(-) (limited to 'drivers/gpu/drm') diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c index 06543ae60706..ef9440166295 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c @@ -325,7 +325,7 @@ void __shmem_writeback(size_t size, struct address_space *mapping) if (folio_mapped(folio)) folio_redirty_for_writepage(&wbc, folio); else - error = shmem_writeout(folio, NULL, NULL); + error = shmem_write_folio(folio); } } diff --git a/drivers/gpu/drm/ttm/ttm_backup.c b/drivers/gpu/drm/ttm/ttm_backup.c index 3c067aadc52d..0c2d53a13b2a 100644 --- a/drivers/gpu/drm/ttm/ttm_backup.c +++ b/drivers/gpu/drm/ttm/ttm_backup.c @@ -160,7 +160,7 @@ ttm_backup_backup_folio(struct file *backup, struct folio *folio, if (writeback && !folio_mapped(to_folio) && folio_clear_dirty_for_io(to_folio)) { folio_set_reclaim(to_folio); - ret = shmem_writeout(to_folio, NULL, NULL); + ret = shmem_write_folio(to_folio); if (!folio_test_writeback(to_folio)) folio_clear_reclaim(to_folio); if (ret == AOP_WRITEPAGE_ACTIVATE) diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h index e729b9b0e38d..5663dff53186 100644 --- a/include/linux/shmem_fs.h +++ b/include/linux/shmem_fs.h @@ -12,8 +12,6 @@ #include #include -struct swap_iocb; - /* inode in-kernel data */ #ifdef CONFIG_TMPFS_QUOTA @@ -123,8 +121,7 @@ static inline bool shmem_mapping(const struct address_space *mapping) void shmem_unlock_mapping(struct address_space *mapping); struct page *shmem_read_mapping_page_gfp(struct address_space *mapping, pgoff_t index, gfp_t gfp_mask); -int shmem_writeout(struct folio *folio, struct swap_iocb **plug, - struct list_head *folio_list); +int shmem_write_folio(struct folio *folio); void shmem_truncate_range(struct inode *inode, loff_t start, uoff_t end); int shmem_unuse(unsigned int type); diff --git a/mm/shmem.c b/mm/shmem.c index 8ea776e52823..d245e01416e9 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1751,7 +1751,12 @@ redirty: folio_mark_dirty(folio); return AOP_WRITEPAGE_ACTIVATE; /* Return with folio locked */ } -EXPORT_SYMBOL_GPL(shmem_writeout); + +int shmem_write_folio(struct folio *folio) +{ + return shmem_writeout(folio, NULL, NULL); +} +EXPORT_SYMBOL_GPL(shmem_write_folio); #if defined(CONFIG_NUMA) && defined(CONFIG_TMPFS) static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) diff --git a/mm/swap.h b/mm/swap.h index 4e4c291bbfde..276b7975a9dc 100644 --- a/mm/swap.h +++ b/mm/swap.h @@ -486,4 +486,8 @@ static inline unsigned int folio_swap_flags(struct folio *folio) } #endif /* CONFIG_SWAP */ + +int shmem_writeout(struct folio *folio, struct swap_iocb **plug, + struct list_head *folio_list); + #endif /* _MM_SWAP_H */ -- cgit