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| author | Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz> | 2011-05-09 13:01:09 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-05-09 16:22:07 -0700 |
| commit | a09a79f66874c905af35d5bb5e5f2fdc7b6b894d (patch) | |
| tree | 9cb2ae1fef7083af91a49c19411e9871e0e59a37 /mm/memory.c | |
| parent | 26822eebb25500fb0776c7c256a6af041e9f538b (diff) | |
| download | lwn-a09a79f66874c905af35d5bb5e5f2fdc7b6b894d.tar.gz lwn-a09a79f66874c905af35d5bb5e5f2fdc7b6b894d.zip | |
Don't lock guardpage if the stack is growing up
Linux kernel excludes guard page when performing mlock on a VMA with
down-growing stack. However, some architectures have up-growing stack
and locking the guard page should be excluded in this case too.
This patch fixes lvm2 on PA-RISC (and possibly other architectures with
up-growing stack). lvm2 calculates number of used pages when locking and
when unlocking and reports an internal error if the numbers mismatch.
[ Patch changed fairly extensively to also fix /proc/<pid>/maps for the
grows-up case, and to move things around a bit to clean it all up and
share the infrstructure with the /proc bits.
Tested on ia64 that has both grow-up and grow-down segments - Linus ]
Signed-off-by: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Tested-by: Tony Luck <tony.luck@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memory.c')
| -rw-r--r-- | mm/memory.c | 16 |
1 files changed, 7 insertions, 9 deletions
diff --git a/mm/memory.c b/mm/memory.c index 27f425378112..61e66f026563 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1412,9 +1412,8 @@ no_page_table: static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr) { - return (vma->vm_flags & VM_GROWSDOWN) && - (vma->vm_start == addr) && - !vma_stack_continue(vma->vm_prev, addr); + return stack_guard_page_start(vma, addr) || + stack_guard_page_end(vma, addr+PAGE_SIZE); } /** @@ -1551,12 +1550,6 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, continue; } - /* - * For mlock, just skip the stack guard page. - */ - if ((gup_flags & FOLL_MLOCK) && stack_guard_page(vma, start)) - goto next_page; - do { struct page *page; unsigned int foll_flags = gup_flags; @@ -1573,6 +1566,11 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, int ret; unsigned int fault_flags = 0; + /* For mlock, just skip the stack guard page. */ + if (foll_flags & FOLL_MLOCK) { + if (stack_guard_page(vma, start)) + goto next_page; + } if (foll_flags & FOLL_WRITE) fault_flags |= FAULT_FLAG_WRITE; if (nonblocking) |