From 3425d6179eae7589bc11800333c9fbb3403e3de0 Mon Sep 17 00:00:00 2001 From: Vlastimil Babka Date: Fri, 6 Aug 2021 17:14:36 +0100 Subject: [PATCH] FROMLIST: 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@suse.cz Signed-off-by: Vlastimil Babka Reported-by: Vijayanand Jitta Reviewed-by: Vijayanand Jitta Acked-by: David Rientjes Cc: Christoph Lameter Cc: Pekka Enberg Cc: Joonsoo Kim Cc: Vinayak Menon Signed-off-by: Andrew Morton Signed-off-by: Mark Brown Bug: 195891241 Link: https://lore.kernel.org/lkml/8a3d992a-473a-467b-28a0-4ad2ff60ab82@suse.cz/ Change-Id: I1f94e8897181b230a7b2965b8943f1bdf20e0a49 Signed-off-by: Vijayanand Jitta --- mm/slub.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index f458b699a3df..0d32e869a64a 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1378,12 +1378,13 @@ parse_slub_debug_flags(char *str, slab_flags_t *flags, char **slabs, bool init) 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. @@ -1395,7 +1396,7 @@ static int __init setup_slub_debug(char *str) 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; @@ -1404,16 +1405,18 @@ static int __init setup_slub_debug(char *str) /* * 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); if ((static_branch_unlikely(&init_on_alloc) ||