The patch titled Subject: mm/cma_debug.c: check for debugfs_create_dir() failure has been added to the -mm tree. Its filename is mm-cma_debug-check-for-null-tmp-in-cma_debugfs_add_one.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-cma_debug-check-for-null-tmp-in-cma_debugfs_add_one.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-cma_debug-check-for-null-tmp-in-cma_debugfs_add_one.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Yue Hu <huyue2@xxxxxxxxxx> Subject: mm/cma_debug.c: check for debugfs_create_dir() failure If debugfs_create_dir() fails, the following debugfs_create_file() will be meaningless since it depends on non-NULL tmp dentry and it will only waste CPU resource. Link: http://lkml.kernel.org/r/20190221040130.8940-2-zbestahu@xxxxxxxxx Signed-off-by: Yue Hu <huyue2@xxxxxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Joe Perches <joe@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- --- a/mm/cma_debug.c~mm-cma_debug-check-for-null-tmp-in-cma_debugfs_add_one +++ a/mm/cma_debug.c @@ -169,6 +169,8 @@ static void cma_debugfs_add_one(struct c scnprintf(name, sizeof(name), "cma-%s", cma->name); tmp = debugfs_create_dir(name, root_dentry); + if (!tmp) + return; debugfs_create_file("alloc", 0200, tmp, cma, &cma_alloc_fops); debugfs_create_file("free", 0200, tmp, cma, &cma_free_fops); _ Patches currently in -mm which might be from huyue2@xxxxxxxxxx are mm-cma_debug-avoid-to-use-global-cma_debugfs_root.patch mm-cma_debug-check-for-null-tmp-in-cma_debugfs_add_one.patch