[PATCH] [60/106] ramfs: fix memleak on no-mmu arch

From: Andi Kleen
Date: Tue Apr 26 2011 - 17:29:12 EST


2.6.35-longterm review patch. If anyone has any objections, please let me know.

------------------
From: Bob Liu <lliubbo@xxxxxxxxx>

commit b836aec53e2bce71de1d5415313380688c851477 upstream.

On no-mmu arch, there is a memleak during shmem test. The cause of this
memleak is ramfs_nommu_expand_for_mapping() added page refcount to 2
which makes iput() can't free that pages.

The simple test file is like this:

int main(void)
{
int i;
key_t k = ftok("/etc", 42);

for ( i=0; i<100; ++i) {
int id = shmget(k, 10000, 0644|IPC_CREAT);
if (id == -1) {
printf("shmget error\n");
}
if(shmctl(id, IPC_RMID, NULL ) == -1) {
printf("shm rm error\n");
return -1;
}
}
printf("run ok...\n");
return 0;
}

And the result:

root:/> free
total used free shared buffers
Mem: 60320 17912 42408 0 0
-/+ buffers: 17912 42408
root:/> shmem
run ok...
root:/> free
total used free shared buffers
Mem: 60320 19096 41224 0 0
-/+ buffers: 19096 41224
root:/> shmem
run ok...
root:/> free
total used free shared buffers
Mem: 60320 20296 40024 0 0
-/+ buffers: 20296 40024
...

After this patch the test result is:(no memleak anymore)

root:/> free
total used free shared buffers
Mem: 60320 16668 43652 0 0
-/+ buffers: 16668 43652
root:/> shmem
run ok...
root:/> free
total used free shared buffers
Mem: 60320 16668 43652 0 0
-/+ buffers: 16668 43652

Signed-off-by: Bob Liu <lliubbo@xxxxxxxxx>
Acked-by: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>

---
fs/ramfs/file-nommu.c | 1 +
1 file changed, 1 insertion(+)

Index: linux-2.6.35.y/fs/ramfs/file-nommu.c
===================================================================
--- linux-2.6.35.y.orig/fs/ramfs/file-nommu.c
+++ linux-2.6.35.y/fs/ramfs/file-nommu.c
@@ -112,6 +112,7 @@ int ramfs_nommu_expand_for_mapping(struc
SetPageDirty(page);

unlock_page(page);
+ put_page(page);
}

return 0;
--
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