kernel.git/mm/vma.c, branch 0x221E-v0.0-v7.0

mm/vma: fix memory leak in __mmap_region()

2026-04-06T18:13:43Z

commit 605f6586ecf7 ("mm/vma: do not leak memory when .mmap_prepare swaps the file") handled the success path by skipping get_file() via file_doesnt_need_get, but missed the error path. When /dev/zero is mmap'd with MAP_SHARED, mmap_zero_prepare() calls shmem_zero_setup_desc() which allocates a new shmem file to back the mapping. If __mmap_new_vma() subsequently fails, this replacement file is never fput()'d - the original is released by ksys_mmap_pgoff(), but nobody releases the new one. Add fput() for the swapped file in the error path. Reproducible with fault injection. FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 1 CPU: 2 UID: 0 PID: 366 Comm: syz.7.14 Not tainted 7.0.0-rc6 #2 PREEMPT(full) Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: dump_stack_lvl+0x164/0x1f0 should_fail_ex+0x525/0x650 should_failslab+0xdf/0x140 kmem_cache_alloc_noprof+0x78/0x630 vm_area_alloc+0x24/0x160 __mmap_region+0xf6b/0x2660 mmap_region+0x2eb/0x3a0 do_mmap+0xc79/0x1240 vm_mmap_pgoff+0x252/0x4c0 ksys_mmap_pgoff+0xf8/0x120 __x64_sys_mmap+0x12a/0x190 do_syscall_64+0xa9/0x580 entry_SYSCALL_64_after_hwframe+0x76/0x7e kmemleak: 1 new suspected memory leaks (see /sys/kernel/debug/kmemleak) BUG: memory leak unreferenced object 0xffff8881118aca80 (size 360): comm "syz.7.14", pid 366, jiffies 4294913255 hex dump (first 32 bytes): 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... ff ff ff ff ff ff ff ff c0 28 4d ae ff ff ff ff .........(M..... backtrace (crc db0f53bc): kmem_cache_alloc_noprof+0x3ab/0x630 alloc_empty_file+0x5a/0x1e0 alloc_file_pseudo+0x135/0x220 __shmem_file_setup+0x274/0x420 shmem_zero_setup_desc+0x9c/0x170 mmap_zero_prepare+0x123/0x140 __mmap_region+0xdda/0x2660 mmap_region+0x2eb/0x3a0 do_mmap+0xc79/0x1240 vm_mmap_pgoff+0x252/0x4c0 ksys_mmap_pgoff+0xf8/0x120 __x64_sys_mmap+0x12a/0x190 do_syscall_64+0xa9/0x580 entry_SYSCALL_64_after_hwframe+0x76/0x7e Found by syzkaller. Link: https://lkml.kernel.org/r/20260331180811.1333348-1-rhkrqnwk98@gmail.com Fixes: 605f6586ecf7 ("mm/vma: do not leak memory when .mmap_prepare swaps the file") Signed-off-by: Sechang Lim Reviewed-by: Lorenzo Stoakes (Oracle) Acked-by: Vlastimil Babka (SUSE) Cc: Jann Horn Cc: Liam Howlett Cc: Lorenzo Stoakes (Oracle) Cc: Pedro Falcato Cc: Signed-off-by: Andrew Morton

mm: make vm_area_desc utilise vma_flags_t only

2026-02-12T23:42:59Z

Now we have eliminated all uses of vm_area_desc->vm_flags, eliminate this field, and have mmap_prepare users utilise the vma_flags_t vm_area_desc->vma_flags field only. As part of this change we alter is_shared_maywrite() to accept a vma_flags_t parameter, and introduce is_shared_maywrite_vm_flags() for use with legacy vm_flags_t flags. We also update struct mmap_state to add a union between vma_flags and vm_flags temporarily until the mmap logic is also converted to using vma_flags_t. Also update the VMA userland tests to reflect this change. Link: https://lkml.kernel.org/r/fd2a2938b246b4505321954062b1caba7acfc77a.1769097829.git.lorenzo.stoakes@oracle.com Signed-off-by: Lorenzo Stoakes Reviewed-by: Pedro Falcato 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 Signed-off-by: Andrew Morton

mm: update secretmem to use VMA flags on mmap_prepare

2026-02-12T23:42:58Z

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: use unmap_desc struct for freeing page tables

2026-02-12T23:42:56Z

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_region() in vms_clear_ptes()

2026-02-12T23:42:56Z

There is no need to open code the vms_clear_ptes() now that unmap_desc struct is used. Link: https://lkml.kernel.org/r/20260121164946.2093480-11-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/vma: use unmap_desc in exit_mmap() and vms_clear_ptes()

2026-02-12T23:42:55Z

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

2026-02-12T23:42:55Z

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/vma: add page table limit to unmap_region()

2026-02-12T23:42:54Z

The unmap_region() calls need to pass through the page table limit for a future patch. No functional changes intended. Link: https://lkml.kernel.org/r/20260121164946.2093480-7-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/memory: add tree limit to free_pgtables()

2026-02-12T23:42:54Z

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

mm/vma: add limits to unmap_region() for vmas

2026-02-12T23:42:54Z

Add a limit to the vma search instead of using the start and end of the one passed in. No functional changes intended. Link: https://lkml.kernel.org/r/20260121164946.2093480-5-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Reviewed-by: David Hildenbrand 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: 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