shm_ids->rw_mutex protects namespace-wide shm info, but not the attributes or contents of individual shm regions, so release it as soon as possible in the restart path.
The SHM_HUGETLB-specific restore code (unfortunately) needs to take mmap_sem, which cannot be taken while holding shm_ids->rw_mutex (see sys_shmdt -> do_munmap -> shm_close), so this is a prerequisite for restoring hugetlb shm regions. Signed-off-by: Nathan Lynch <[email protected]> --- ipc/checkpoint_shm.c | 8 ++++---- 1 files changed, 4 insertions(+), 4 deletions(-) diff --git a/ipc/checkpoint_shm.c b/ipc/checkpoint_shm.c index a929e33..69ba35a 100644 --- a/ipc/checkpoint_shm.c +++ b/ipc/checkpoint_shm.c @@ -284,19 +284,19 @@ int restore_ipc_shm(struct ckpt_ctx *ctx, struct ipc_namespace *ns) /* this is safe because no unauthorized access is possible */ ipc_unlock(ipc); + up_write(&shm_ids->rw_mutex); ret = load_ipc_shm_hdr(ctx, h, shp); if (ret < 0) - goto mutex; + goto fput; /* deposit in objhash and read contents in */ ret = ckpt_obj_insert(ctx, file, h->objref, CKPT_OBJ_FILE); if (ret < 0) - goto mutex; + goto fput; ret = restore_memory_contents(ctx, file->f_dentry->d_inode); - mutex: +fput: fput(file); - up_write(&shm_ids->rw_mutex); /* discard this shmid if error and deferqueue wasn't set */ if (ret < 0 && !(h->perms.mode & SHM_DEST)) { -- 1.7.2.2 _______________________________________________ Containers mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list [email protected] https://openvz.org/mailman/listinfo/devel
