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authorAndrey Ryabinin <a.ryabinin@samsung.com>2014-07-30 16:08:35 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-07-30 17:16:13 -0700
commitb4903d6e8408e6137ee4666ee67ec566b74a0f05 (patch)
tree2db6b545dd1e56bac8602974fe74ca0cc773d67a
parent2bcf2e92c3918ce62ab4e934256e47e9a16d19c3 (diff)
downloadlinux-b4903d6e8408e6137ee4666ee67ec566b74a0f05.tar.gz
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>
-rw-r--r--mm/memory.c21
1 files changed, 12 insertions, 9 deletions
diff --git a/mm/memory.c b/mm/memory.c
index 7e8d8205b61..8b44f765b64 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,