On Fri, Aug 30, 2013 at 10:02:36PM -0400, Waiman Long wrote:
> I slapped in the code segment, and the following was logged:
>
> [ 340.871590] type = tmpfs
> [ 340.871712] [<ffffffff8116c5bd>] __fput+0x23d/0x270
> [ 340.871715] [<ffffffff8116c699>] ____fput+0x9/0x10
> [ 340.871719] [<ffffffff81068ae1>] task_work_run+0xb1/0xe0
> [ 340.871724] [<ffffffff81002990>] do_notify_resume+0x80/0x1b0
> [ 340.871728] [<ffffffff811ed120>] ? ipc_lock+0x30/0x50
> [ 340.871732] [<ffffffff8113a356>] ? remove_vma+0x56/0x60
> [ 340.871736] [<ffffffff8113c1bf>] ? do_munmap+0x34f/0x380
> [ 340.871741] [<ffffffff814a5fda>] int_signal+0x12/0x17
> [ 340.871744] ---[ end trace aafa6c45f3388d65 ]---
Aha... OK, I see what's going on. We end up with shm_mnt *not* marked
as long-living vfsmount, even though it lives forever. See if the
following helps; if it does (and I very much expect it to), we want to
put it in -stable. As it is, you get slow path in mntput() each time
a file created by shmem_file_setup() gets closed. For no reason whatsoever...
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
diff --git a/mm/shmem.c b/mm/shmem.c
index e43dc55..445162c 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2615,7 +2615,7 @@ int shmem_fill_super(struct super_block *sb, void *data, int silent)
* tmpfs instance, limiting inodes to one per page of lowmem;
* but the internal instance is left unlimited.
*/
- if (!(sb->s_flags & MS_NOUSER)) {
+ if (!(sb->s_flags & MS_KERNMOUNT)) {
sbinfo->max_blocks = shmem_default_max_blocks();
sbinfo->max_inodes = shmem_default_max_inodes();
if (shmem_parse_options(data, sbinfo, false)) {
@@ -2831,8 +2831,7 @@ int __init shmem_init(void)
goto out2;
}
- shm_mnt = vfs_kern_mount(&shmem_fs_type, MS_NOUSER,
- shmem_fs_type.name, NULL);
+ shm_mnt = kern_mount(&shmem_fs_type);
if (IS_ERR(shm_mnt)) {
error = PTR_ERR(shm_mnt);
printk(KERN_ERR "Could not kern_mount tmpfs\n");
--
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