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| author | Andrey Ryabinin <a.ryabinin@samsung.com> | 2014-07-31 01:08:35 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-07-31 02:16:13 +0200 |
| commit | b4903d6e8408e6137ee4666ee67ec566b74a0f05 (patch) | |
| tree | 2db6b545dd1e56bac8602974fe74ca0cc773d67a /mm/memory.c | |
| parent | memcg: oom_notify use-after-free fix (diff) | |
| download | linux-b4903d6e8408e6137ee4666ee67ec566b74a0f05.tar.xz linux-b4903d6e8408e6137ee4666ee67ec566b74a0f05.zip | |
mm: debugfs: move rounddown_pow_of_two() out from do_fault path
do_fault_around() expects fault_around_bytes rounded down to nearest page
order. Instead of calling rounddown_pow_of_two every time in
fault_around_pages()/fault_around_mask() we could do round down when user
changes fault_around_bytes via debugfs interface.
This also fixes bug when user set fault_around_bytes to 0. Result of
rounddown_pow_of_two(0) is not defined, therefore fault_around_bytes == 0
doesn't work without this patch.
Let's set fault_around_bytes to PAGE_SIZE if user sets to something less
than PAGE_SIZE
[akpm@linux-foundation.org: tweak code layout]
Fixes: a9b0f861("mm: nominate faultaround area in bytes rather than page order")
Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: <stable@vger.kernel.org> [3.15.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memory.c')
| -rw-r--r-- | mm/memory.c | 21 |
1 files changed, 12 insertions, 9 deletions
diff --git a/mm/memory.c b/mm/memory.c index 7e8d8205b610..8b44f765b645 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2758,23 +2758,18 @@ void do_set_pte(struct vm_area_struct *vma, unsigned long address, update_mmu_cache(vma, address, pte); } -static unsigned long fault_around_bytes = 65536; +static unsigned long fault_around_bytes = rounddown_pow_of_two(65536); -/* - * fault_around_pages() and fault_around_mask() round down fault_around_bytes - * to nearest page order. It's what do_fault_around() expects to see. - */ static inline unsigned long fault_around_pages(void) { - return rounddown_pow_of_two(fault_around_bytes) / PAGE_SIZE; + return fault_around_bytes >> PAGE_SHIFT; } static inline unsigned long fault_around_mask(void) { - return ~(rounddown_pow_of_two(fault_around_bytes) - 1) & PAGE_MASK; + return ~(fault_around_bytes - 1) & PAGE_MASK; } - #ifdef CONFIG_DEBUG_FS static int fault_around_bytes_get(void *data, u64 *val) { @@ -2782,11 +2777,19 @@ static int fault_around_bytes_get(void *data, u64 *val) return 0; } +/* + * fault_around_pages() and fault_around_mask() expects fault_around_bytes + * rounded down to nearest page order. It's what do_fault_around() expects to + * see. + */ static int fault_around_bytes_set(void *data, u64 val) { if (val / PAGE_SIZE > PTRS_PER_PTE) return -EINVAL; - fault_around_bytes = val; + if (val > PAGE_SIZE) + fault_around_bytes = rounddown_pow_of_two(val); + else + fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */ return 0; } DEFINE_SIMPLE_ATTRIBUTE(fault_around_bytes_fops, |