kernel/linux.git/mm/mmap.c, branch v7.1

mm: convert do_brk_flags() to use vma_flags_t

2026-04-05T20:53:40+00:00

In order to be able to do this, we need to change VM_DATA_DEFAULT_FLAGS and friends and update the architecture-specific definitions also. We then have to update some KSM logic to handle VMA flags, and introduce VMA_STACK_FLAGS to define the vma_flags_t equivalent of VM_STACK_FLAGS. We also introduce two helper functions for use during the time we are converting legacy flags to vma_flags_t values - vma_flags_to_legacy() and legacy_to_vma_flags(). This enables us to iteratively make changes to break these changes up into separate parts. We use these explicitly here to keep VM_STACK_FLAGS around for certain users which need to maintain the legacy vm_flags_t values for the time being. We are no longer able to rely on the simple VM_xxx being set to zero if the feature is not enabled, so in the case of VM_DROPPABLE we introduce VMA_DROPPABLE as the vma_flags_t equivalent, which is set to EMPTY_VMA_FLAGS if the droppable flag is not available. While we're here, we make the description of do_brk_flags() into a kdoc comment, as it almost was already. We use vma_flags_to_legacy() to not need to update the vm_get_page_prot() logic as this time. Note that in create_init_stack_vma() we have to replace the BUILD_BUG_ON() with a VM_WARN_ON_ONCE() as the tested values are no longer build time available. We also update mprotect_fixup() to use VMA flags where possible, though we have to live with a little duplication between vm_flags_t and vma_flags_t values for the time being until further conversions are made. While we're here, update VM_SPECIAL to be defined in terms of VMA_SPECIAL_FLAGS now we have vma_flags_to_legacy(). Finally, we update the VMA tests to reflect these changes. Link: https://lkml.kernel.org/r/d02e3e45d9a33d7904b149f5604904089fd640ae.1774034900.git.ljs@kernel.org Signed-off-by: Lorenzo Stoakes (Oracle) Acked-by: Paul Moore [SELinux] Acked-by: Vlastimil Babka (SUSE) Cc: Albert Ou Cc: Alexander Gordeev Cc: Alexandre Ghiti Cc: Al Viro Cc: Anton Ivanov Cc: "Borislav Petkov (AMD)" Cc: Catalin Marinas Cc: Chengming Zhou Cc: Christian Borntraeger Cc: Christian Brauner Cc: David Hildenbrand Cc: Dinh Nguyen Cc: Heiko Carstens Cc: "H. Peter Anvin" Cc: Huacai Chen Cc: Ingo Molnar Cc: Jan Kara Cc: Jann Horn Cc: Johannes Berg Cc: Kees Cook Cc: Liam Howlett Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Michal Hocko Cc: Mike Rapoport Cc: Nicholas Piggin Cc: Ondrej Mosnacek Cc: Palmer Dabbelt Cc: Pedro Falcato Cc: Richard Weinberger Cc: Russell King Cc: Stephen Smalley Cc: Suren Baghdasaryan Cc: Sven Schnelle Cc: Thomas Bogendoerfer Cc: Vasily Gorbik Cc: Vineet Gupta Cc: WANG Xuerui Cc: Will Deacon Cc: xu xin Signed-off-by: Andrew Morton

mm: unexport vm_brk_flags() and eliminate vm_flags parameter

2026-04-05T20:53:39+00:00

This function is only used by elf_load(), and that is a static function that doesn't need an exported symbol to invoke an internal function, so un-EXPORT_SYMBOLS() it. Also, the vm_flags parameter is unnecessary, as we only ever set VM_EXEC, so simply make this parameter a boolean. While we're here, clean up the mm.h definitions for the various vm_xxx() helpers so we actually specify parameter names and elide the redundant extern's. Link: https://lkml.kernel.org/r/7bada48ddf3f9dbd3e6c4fc50ec2f4de97706f52.1774034900.git.ljs@kernel.org Signed-off-by: Lorenzo Stoakes (Oracle) Acked-by: Vlastimil Babka (SUSE) Cc: Albert Ou Cc: Alexander Gordeev Cc: Alexandre Ghiti Cc: Al Viro Cc: Anton Ivanov Cc: "Borislav Petkov (AMD)" Cc: Catalin Marinas Cc: Chengming Zhou Cc: Christian Borntraeger Cc: Christian Brauner Cc: David Hildenbrand Cc: Dinh Nguyen Cc: Heiko Carstens Cc: "H. Peter Anvin" Cc: Huacai Chen Cc: Ingo Molnar Cc: Jan Kara Cc: Jann Horn Cc: Johannes Berg Cc: Kees Cook Cc: Liam Howlett Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Michal Hocko Cc: Mike Rapoport Cc: Nicholas Piggin Cc: Ondrej Mosnacek Cc: Palmer Dabbelt Cc: Paul Moore Cc: Pedro Falcato Cc: Richard Weinberger Cc: Russell King Cc: Stephen Smalley Cc: Suren Baghdasaryan Cc: Sven Schnelle Cc: Thomas Bogendoerfer Cc: Vasily Gorbik Cc: Vineet Gupta Cc: WANG Xuerui Cc: Will Deacon Cc: xu xin Signed-off-by: Andrew Morton

mm: abstract reading sysctl_max_map_count, and READ_ONCE()

2026-04-05T20:53:28+00:00

Concurrent reads and writes of sysctl_max_map_count are possible, so we should READ_ONCE() and WRITE_ONCE(). The sysctl procfs logic already enforces WRITE_ONCE(), so abstract the read side with get_sysctl_max_map_count(). While we're here, also move the field to mm/internal.h and add the getter there since only mm interacts with it, there's no need for anybody else to have access. Finally, update the VMA userland tests to reflect the change. Link: https://lkml.kernel.org/r/0715259eb37cbdfde4f9e5db92a20ec7110a1ce5.1773249037.git.ljs@kernel.org Signed-off-by: Lorenzo Stoakes (Oracle) Reviewed-by: Pedro Falcato Cc: Jann Horn Cc: Jianzhou Zhao Cc: Liam Howlett Cc: Michal Hocko Cc: Mike Rapoport Cc: Oscar Salvador Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm: update secretmem to use VMA flags on mmap_prepare

2026-02-12T23:42:58+00:00

This patch updates secretmem to use the new vma_flags_t type which will soon supersede vm_flags_t altogether. In order to make this change we also have to update mlock_future_ok(), we replace the vm_flags_t parameter with a simple boolean is_vma_locked one, which also simplifies the invocation here. This is laying the groundwork for eliminating the vm_flags_t in vm_area_desc and more broadly throughout the kernel. No functional changes intended. [lorenzo.stoakes@oracle.com: fix check_brk_limits(), per Chris] Link: https://lkml.kernel.org/r/3aab9ab1-74b4-405e-9efb-08fc2500c06e@lucifer.local Link: https://lkml.kernel.org/r/a243a09b0a5d0581e963d696de1735f61f5b2075.1769097829.git.lorenzo.stoakes@oracle.com Signed-off-by: Lorenzo Stoakes Reviewed-by: Liam R. Howlett Cc: Baolin Wang Cc: Barry Song Cc: David Hildenbrand Cc: Dev Jain Cc: Jason Gunthorpe Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Zi Yan Cc: Damien Le Moal Cc: "Darrick J. Wong" Cc: Jarkko Sakkinen Cc: Yury Norov Cc: Chris Mason Cc: Pedro Falcato Signed-off-by: Andrew Morton

mm: update hugetlbfs to use VMA flags on mmap_prepare

2026-02-12T23:42:57+00:00

In order to update all mmap_prepare users to utilising the new VMA flags type vma_flags_t and associated helper functions, we start by updating hugetlbfs which has a lot of additional logic that requires updating to make this change. This is laying the groundwork for eliminating the vm_flags_t from struct vm_area_desc and using vma_flags_t only, which further lays the ground for removing the deprecated vm_flags_t type altogether. No functional changes intended. Link: https://lkml.kernel.org/r/9226bec80c9aa3447cc2b83354f733841dba8a50.1769097829.git.lorenzo.stoakes@oracle.com Signed-off-by: Lorenzo Stoakes Reviewed-by: Liam R. Howlett Cc: Baolin Wang Cc: Barry Song Cc: David Hildenbrand Cc: Dev Jain Cc: Jason Gunthorpe Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Zi Yan Cc: Damien Le Moal Cc: "Darrick J. Wong" Cc: Jarkko Sakkinen Cc: Yury Norov Cc: Chris Mason Cc: Pedro Falcato Signed-off-by: Andrew Morton

mm: use unmap_desc struct for freeing page tables

2026-02-12T23:42:56+00:00

Pass through the unmap_desc to free_pgtables() because it almost has everything necessary and is already on the stack. Updates testing code as necessary. No functional changes intended. [Liam.Howlett@oracle.com: fix up unmap desc use on exit_mmap()] Link: https://lkml.kernel.org/r/20260210214214.364856-1-Liam.Howlett@oracle.com Link: https://lkml.kernel.org/r/20260121164946.2093480-12-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Reviewed-by: Lorenzo Stoakes Cc: Suren Baghdasaryan Cc: Baoquan He Cc: Barry Song Cc: Chris Li Cc: David Hildenbrand Cc: David Hildenbrand Cc: Jann Horn Cc: Kairui Song Cc: Kemeng Shi Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Mike Rapoport Cc: Nhat Pham Cc: Pedro Falcato Cc: SeongJae Park Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm/vma: use unmap_desc in exit_mmap() and vms_clear_ptes()

2026-02-12T23:42:55+00:00

Convert vms_clear_ptes() to use unmap_desc to call unmap_vmas() instead of the large argument list. The UNMAP_STATE() cannot be used because the vma iterator in the vms does not point to the correct maple state (mas_detach), and the tree_end will be set incorrectly. Setting up the arguments manually avoids setting the struct up incorrectly and doing extra work to get the correct pagetable range. exit_mmap() also calls unmap_vmas() with many arguments. Using the unmap_all_init() function to set the unmap descriptor for all vmas makes this a bit easier to read. Update to the vma test code is necessary to ensure testing continues to function. No functional changes intended. Link: https://lkml.kernel.org/r/20260121164946.2093480-10-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Cc: Baoquan He Cc: Barry Song Cc: Chris Li Cc: David Hildenbrand Cc: David Hildenbrand Cc: Jann Horn Cc: Kairui Song Cc: Kemeng Shi Cc: Lorenzo Stoakes Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Mike Rapoport Cc: Nhat Pham Cc: Pedro Falcato Cc: SeongJae Park Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm: introduce unmap_desc struct to reduce function arguments

2026-02-12T23:42:55+00:00

The unmap_region code uses a number of arguments that could use better documentation. With the addition of a descriptor for unmap (called unmap_desc), the arguments can be more self-documenting and increase the descriptions within the declaration. No functional change intended Link: https://lkml.kernel.org/r/20260121164946.2093480-9-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Reviewed-by: Lorenzo Stoakes Reviewed-by: Pedro Falcato Cc: Baoquan He Cc: Barry Song Cc: Chris Li Cc: David Hildenbrand Cc: David Hildenbrand Cc: Jann Horn Cc: Kairui Song Cc: Kemeng Shi Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Mike Rapoport Cc: Nhat Pham Cc: SeongJae Park Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm: change dup_mmap() recovery

2026-02-12T23:42:55+00:00

When the dup_mmap() fails during the vma duplication or setup, don't write the XA_ZERO entry in the vma tree. Instead, destroy the tree and free the new resources, leaving an empty vma tree. Using XA_ZERO introduced races where the vma could be found between dup_mmap() dropping all locks and exit_mmap() taking the locks. The race can occur because the mm can be reached through the other trees via successfully copied vmas and other methods such as the swapoff code. XA_ZERO was marking the location to stop vma removal and pagetable freeing. The newly created arguments to the unmap_vmas() and free_pgtables() serve this function. Replacing the XA_ZERO entry use with the new argument list also means the checks for xa_is_zero() are no longer necessary so these are also removed. Note that dup_mmap() now cleans up when ALL vmas are successfully copied, but the dup_mmap() fails to completely set up some other aspect of the duplication. Link: https://lkml.kernel.org/r/20260121164946.2093480-8-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Reviewed-by: Lorenzo Stoakes Reviewed-by: Pedro Falcato Reviewed-by: Suren Baghdasaryan Cc: Baoquan He Cc: Barry Song Cc: Chris Li Cc: David Hildenbrand Cc: David Hildenbrand Cc: Jann Horn Cc: Kairui Song Cc: Kemeng Shi Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Mike Rapoport Cc: Nhat Pham Cc: SeongJae Park Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm/memory: add tree limit to free_pgtables()

2026-02-12T23:42:54+00:00

The ceiling and tree search limit need to be different arguments for the future change in the failed fork attempt. The ceiling and floor variables are not very descriptive, so change them to pg_start/pg_end. Adding a new variable for the vma_end to the function as it will differ from the pg_end in the later patches in the series. Add a kernel doc about the free_pgtables() function. Test code also updated. No functional changes intended. Link: https://lkml.kernel.org/r/20260121164946.2093480-6-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Reviewed-by: Lorenzo Stoakes Reviewed-by: Pedro Falcato Cc: Baoquan He Cc: Barry Song Cc: Chris Li Cc: David Hildenbrand Cc: David Hildenbrand Cc: Jann Horn Cc: Kairui Song Cc: Kemeng Shi Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Mike Rapoport Cc: Nhat Pham Cc: SeongJae Park Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton