| Message ID | 20230828035248.678960-1-anshuman.khandual@arm.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/mmap: Define DEFAULT_STACK_GUARD_GAP | expand |
On Mon, Aug 28, 2023 at 09:22:48AM +0530, Anshuman Khandual wrote: > This just defines a macro constant i.e DEFAULT_STACK_GUARD_GAP representing > the default gap, guarding the stack mapping. This does not cause functional > changes. But why have you done it at all?
On 8/29/23 18:02, Matthew Wilcox wrote: > On Mon, Aug 28, 2023 at 09:22:48AM +0530, Anshuman Khandual wrote: >> This just defines a macro constant i.e DEFAULT_STACK_GUARD_GAP representing >> the default gap, guarding the stack mapping. This does not cause functional >> changes. > > But why have you done it at all? Just as a normal cleanup which also improves readability.
On Wed, Aug 30, 2023 at 08:25:45AM +0530, Anshuman Khandual wrote: > > > On 8/29/23 18:02, Matthew Wilcox wrote: > > On Mon, Aug 28, 2023 at 09:22:48AM +0530, Anshuman Khandual wrote: > >> This just defines a macro constant i.e DEFAULT_STACK_GUARD_GAP representing > >> the default gap, guarding the stack mapping. This does not cause functional > >> changes. > > > > But why have you done it at all? > > Just as a normal cleanup which also improves readability. hard disagree. NAK this patch.
diff --git a/include/linux/mman.h b/include/linux/mman.h index cee1e4b566d8..cbcd20a071c0 100644 --- a/include/linux/mman.h +++ b/include/linux/mman.h @@ -8,6 +8,9 @@ #include <linux/atomic.h> #include <uapi/linux/mman.h> +/* Default gap for stack mapping is 256 pages */ +#define DEFAULT_STACK_GUARD_GAP (256UL << PAGE_SHIFT) + /* * Arrange for legacy / undefined architecture specific flags to be * ignored by mmap handling code. diff --git a/mm/mmap.c b/mm/mmap.c index 3937479d0e07..8679750333bb 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2120,7 +2120,7 @@ int expand_downwards(struct vm_area_struct *vma, unsigned long address) } /* enforced gap between the expanding stack and other mappings. */ -unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT; +unsigned long stack_guard_gap = DEFAULT_STACK_GUARD_GAP; static int __init cmdline_parse_stack_guard_gap(char *p) {
This just defines a macro constant i.e DEFAULT_STACK_GUARD_GAP representing the default gap, guarding the stack mapping. This does not cause functional changes. Cc: Andrew Morton <akpm@linux-foundation.org> Cc: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> --- include/linux/mman.h | 3 +++ mm/mmap.c | 2 +- 2 files changed, 4 insertions(+), 1 deletion(-)