From: Vlastimil Babka <vbabka@xxxxxxx> Subject: mm: slub: fix slub_debug disabling for list of slabs Vijayanand Jitta reports: Consider the scenario where CONFIG_SLUB_DEBUG_ON is set and we would want to disable slub_debug for few slabs. Using boot parameter with slub_debug=-,slab_name syntax doesn't work as expected i.e; only disabling debugging for the specified list of slabs. Instead it disables debugging for all slabs, which is wrong. This patch fixes it by delaying the moment when the global slub_debug flags variable is updated. In case a "slub_debug=-,slab_name" has been passed, the global flags remain as initialized (depending on CONFIG_SLUB_DEBUG_ON enabled or disabled) and are not simply reset to 0. Link: https://lkml.kernel.org/r/8a3d992a-473a-467b-28a0-4ad2ff60ab82@xxxxxxx Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> Reported-by: Vijayanand Jitta <vjitta@xxxxxxxxxxxxxx> Reviewed-by: Vijayanand Jitta <vjitta@xxxxxxxxxxxxxx> Acked-by: David Rientjes <rientjes@xxxxxxxxxx> Cc: Christoph Lameter <cl@xxxxxxxxx> Cc: Pekka Enberg <penberg@xxxxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Cc: Vinayak Menon <vinmenon@xxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/slub.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) --- a/mm/slub.c~mm-slub-fix-slub_debug-disablement-for-list-of-slabs +++ a/mm/slub.c @@ -1400,12 +1400,13 @@ check_slabs: static int __init setup_slub_debug(char *str) { slab_flags_t flags; + slab_flags_t global_flags; char *saved_str; char *slab_list; bool global_slub_debug_changed = false; bool slab_list_specified = false; - slub_debug = DEBUG_DEFAULT_FLAGS; + global_flags = DEBUG_DEFAULT_FLAGS; if (*str++ != '=' || !*str) /* * No options specified. Switch on full debugging. @@ -1417,7 +1418,7 @@ static int __init setup_slub_debug(char str = parse_slub_debug_flags(str, &flags, &slab_list, true); if (!slab_list) { - slub_debug = flags; + global_flags = flags; global_slub_debug_changed = true; } else { slab_list_specified = true; @@ -1426,16 +1427,18 @@ static int __init setup_slub_debug(char /* * For backwards compatibility, a single list of flags with list of - * slabs means debugging is only enabled for those slabs, so the global - * slub_debug should be 0. We can extended that to multiple lists as + * slabs means debugging is only changed for those slabs, so the global + * slub_debug should be unchanged (0 or DEBUG_DEFAULT_FLAGS, depending + * on CONFIG_SLUB_DEBUG_ON). We can extended that to multiple lists as * long as there is no option specifying flags without a slab list. */ if (slab_list_specified) { if (!global_slub_debug_changed) - slub_debug = 0; + global_flags = slub_debug; slub_debug_string = saved_str; } out: + slub_debug = global_flags; if (slub_debug != 0 || slub_debug_string) static_branch_enable(&slub_debug_enabled); else _
