From: Andrew Perepechko <pa...@cloudlinux.com>
Currently, shmem_lock immediately and
unconditionally uncharges what it has
just charged for a lock request.
This, indeed, causes a double uncharge
with something like the following:
shmid = shmget(12345, 8192, IPC_CREAT | 0666);
rc = shmctl(shmid, SHM_LOCK, NULL);
shmctl(shmid, IPC_RMID, 0);
with the following in the kernel log:
[ 455.815025] Uncharging too much 2 h 0, res lockedpages ub 0
Signed-off-by: Andrew Perepechko <pa...@cloudlinux.com>
---
mm/shmem.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/mm/shmem.c b/mm/shmem.c
index a6b3e30..d09a230 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1359,11 +1359,13 @@ int shmem_lock(struct file *file, int lock, struct
user_struct *user)
mapping_set_unevictable(file->f_mapping);
}
if (!lock && (info->flags & VM_LOCKED) && user) {
+ ub_lockedshm_uncharge(info, inode->i_size);
user_shm_unlock(inode->i_size, user);
info->flags &= ~VM_LOCKED;
mapping_clear_unevictable(file->f_mapping);
}
- retval = 0;
+ spin_unlock(&info->lock);
+ return 0;
out_nomem:
ub_lockedshm_uncharge(info, inode->i_size);
--
1.9.1
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