From: Suren Baghdasaryan Date: Sat, 8 Jul 2023 19:12:10 +0000 (-0700) Subject: mm: lock a vma before stack expansion X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=c137381f71aec755fbf47cd4e9bd4dce752c054c;p=linux.git mm: lock a vma before stack expansion With recent changes necessitating mmap_lock to be held for write while expanding a stack, per-VMA locks should follow the same rules and be write-locked to prevent page faults into the VMA being expanded. Add the necessary locking. Cc: stable@vger.kernel.org Signed-off-by: Suren Baghdasaryan Signed-off-by: Linus Torvalds --- diff --git a/mm/mmap.c b/mm/mmap.c index 204ddcd52625a..c66e4622a5576 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1977,6 +1977,8 @@ static int expand_upwards(struct vm_area_struct *vma, unsigned long address) return -ENOMEM; } + /* Lock the VMA before expanding to prevent concurrent page faults */ + vma_start_write(vma); /* * vma->vm_start/vm_end cannot change under us because the caller * is required to hold the mmap_lock in read mode. We need the @@ -2064,6 +2066,8 @@ int expand_downwards(struct vm_area_struct *vma, unsigned long address) return -ENOMEM; } + /* Lock the VMA before expanding to prevent concurrent page faults */ + vma_start_write(vma); /* * vma->vm_start/vm_end cannot change under us because the caller * is required to hold the mmap_lock in read mode. We need the