Commit-ID: 2ed11312eb19506c027e7cac039994ad42a9cb2c
Gitweb: http://git.kernel.org/tip/2ed11312eb19506c027e7cac039994ad42a9cb2c
Author: Kan Liang <kan.liang@xxxxxxxxx>
AuthorDate: Mon, 2 Mar 2015 02:14:26 -0500
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Mon, 2 Mar 2015 18:25:38 -0300
Revert "perf: Remove the extra validity check on nr_pages"
This reverts commit 74390aa55678 ("perf: Remove the extra validity check
on nr_pages")
nr_pages equals to number of pages - 1 in perf_mmap. So nr_pages = 0 is
valid.
So the nr_pages != 0 && !is_power_of_2(nr_pages) are all
needed for checking. Otherwise, for example, perf test 6 failed.
# perf test 6
6: x86 rdpmc test :Error:
mmap() syscall returned with (Invalid argument)
FAILED!
Signed-off-by: Kan Liang <kan.liang@xxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Kaixu Xia <xiakaixu@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1425280466-7830-1-git-send-email-kan.liang@xxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
kernel/events/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index af924bc..8bb20cc 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4446,7 +4446,7 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
* If we have rb pages ensure they're a power-of-two number, so we
* can do bitmasks instead of modulo.
*/
- if (!is_power_of_2(nr_pages))
+ if (nr_pages != 0 && !is_power_of_2(nr_pages))
return -EINVAL;
if (vma_size != PAGE_SIZE * (1 + nr_pages))
--
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