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author | Linus Torvalds <torvalds@linux-foundation.org> | 2023-06-24 13:45:51 -0700 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-07-01 13:16:25 +0200 |
commit | e6bbad75712a97b9b16433563c1358652a33003e (patch) | |
tree | f6b5576d36aeb448ba285be34556ad9a3ef96465 /mm/nommu.c | |
parent | c4b31d1b694e101cae7469a20762647185e11721 (diff) | |
download | linux-e6bbad75712a97b9b16433563c1358652a33003e.tar.gz |
mm: always expand the stack with the mmap write lock held
commit 8d7071af890768438c14db6172cc8f9f4d04e184 upstream This finishes the job of always holding the mmap write lock when extending the user stack vma, and removes the 'write_locked' argument from the vm helper functions again. For some cases, we just avoid expanding the stack at all: drivers and page pinning really shouldn't be extending any stacks. Let's see if any strange users really wanted that. It's worth noting that architectures that weren't converted to the new lock_mm_and_find_vma() helper function are left using the legacy "expand_stack()" function, but it has been changed to drop the mmap_lock and take it for writing while expanding the vma. This makes it fairly straightforward to convert the remaining architectures. As a result of dropping and re-taking the lock, the calling conventions for this function have also changed, since the old vma may no longer be valid. So it will now return the new vma if successful, and NULL - and the lock dropped - if the area could not be extended. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> [6.1: Patch drivers/iommu/io-pgfault.c instead] Signed-off-by: Samuel Mendoza-Jonas <samjonas@amazon.com> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm/nommu.c')
-rw-r--r-- | mm/nommu.c | 18 |
1 files changed, 7 insertions, 11 deletions
diff --git a/mm/nommu.c b/mm/nommu.c index 2772d6b332ff..b44ed69c109a 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -682,24 +682,20 @@ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) EXPORT_SYMBOL(find_vma); /* - * find a VMA - * - we don't extend stack VMAs under NOMMU conditions - */ -struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr) -{ - return find_vma(mm, addr); -} - -/* * expand a stack to a given address * - not supported under NOMMU conditions */ -int expand_stack_locked(struct vm_area_struct *vma, unsigned long address, - bool write_locked) +int expand_stack_locked(struct vm_area_struct *vma, unsigned long addr) { return -ENOMEM; } +struct vm_area_struct *expand_stack(struct mm_struct *mm, unsigned long addr) +{ + mmap_read_unlock(mm); + return NULL; +} + /* * look up the first VMA exactly that exactly matches addr * - should be called with mm->mmap_lock at least held readlocked |