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author | Peter Feiner <pfeiner@google.com> | 2014-10-10 00:28:32 +0200 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-10-10 04:25:58 +0200 |
commit | 81d0fa623c5b8dbd5279d9713094b0f9b0a00fb4 (patch) | |
tree | 840455ffeafaef31a53b94dc74df80d2561c713e /scripts/mksysmap | |
parent | mm: page_alloc: default node-ordering on 64-bit NUMA, zone-ordering on 32-bit (diff) | |
download | linux-81d0fa623c5b8dbd5279d9713094b0f9b0a00fb4.tar.xz linux-81d0fa623c5b8dbd5279d9713094b0f9b0a00fb4.zip |
mm: softdirty: unmapped addresses between VMAs are clean
If a /proc/pid/pagemap read spans a [VMA, an unmapped region, then a
VM_SOFTDIRTY VMA], the virtual pages in the unmapped region are reported
as softdirty. Here's a program to demonstrate the bug:
int main() {
const uint64_t PAGEMAP_SOFTDIRTY = 1ul << 55;
uint64_t pme[3];
int fd = open("/proc/self/pagemap", O_RDONLY);;
char *m = mmap(NULL, 3 * getpagesize(), PROT_READ,
MAP_ANONYMOUS | MAP_SHARED, -1, 0);
munmap(m + getpagesize(), getpagesize());
pread(fd, pme, 24, (unsigned long) m / getpagesize() * 8);
assert(pme[0] & PAGEMAP_SOFTDIRTY); /* passes */
assert(!(pme[1] & PAGEMAP_SOFTDIRTY)); /* fails */
assert(pme[2] & PAGEMAP_SOFTDIRTY); /* passes */
return 0;
}
(Note that all pages in new VMAs are softdirty until cleared).
Tested:
Used the program given above. I'm going to include this code in
a selftest in the future.
[n-horiguchi@ah.jp.nec.com: prevent pagemap_pte_range() from overrunning]
Signed-off-by: Peter Feiner <pfeiner@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Jamie Liu <jamieliu@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'scripts/mksysmap')
0 files changed, 0 insertions, 0 deletions