From: Stephen Boyd <swboyd@xxxxxxxxxxxx> Subject: slub: restore slub_debug=- behavior Petch series "slub: Print non-hashed pointers in slub debugging", v3. I was doing some debugging recently and noticed that my pointers were being hashed while slub_debug was on the kernel commandline. Let's force on the no hash pointer option when slub_debug is on the kernel commandline so that the prints are more meaningful. The first two patches are something else I noticed while looking at the code. The message argument is never used so the debugging messages are not as clear as they could be and the slub_debug=- behavior seems to be busted. Then there's a printf fixup from Joe and the final patch is the one that force disables pointer hashing. This patch (of 4): Passing slub_debug=- on the kernel commandline is supposed to disable slub debugging. This is especially useful with CONFIG_SLUB_DEBUG_ON where the default is to have slub debugging enabled in the build. Due to some code reorganization this behavior was dropped, but the code to make it work mostly stuck around. Restore the previous behavior by disabling the static key when we parse the commandline and see that we're trying to disable slub debugging. Link: https://lkml.kernel.org/r/20210601182202.3011020-1-swboyd@xxxxxxxxxxxx Link: https://lkml.kernel.org/r/20210601182202.3011020-2-swboyd@xxxxxxxxxxxx Fixes: ca0cab65ea2b ("mm, slub: introduce static key for slub_debug()") Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx> Acked-by: Vlastimil Babka <vbabka@xxxxxxx> Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx> Cc: Christoph Lameter <cl@xxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Joe Perches <joe@xxxxxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Cc: Pekka Enberg <penberg@xxxxxxxxxx> Cc: Petr Mladek <pmladek@xxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/slub.c | 2 ++ 1 file changed, 2 insertions(+) --- a/mm/slub.c~slub-restore-slub_debug=-behavior +++ a/mm/slub.c @@ -1429,6 +1429,8 @@ static int __init setup_slub_debug(char out: if (slub_debug != 0 || slub_debug_string) static_branch_enable(&slub_debug_enabled); + else + static_branch_disable(&slub_debug_enabled); if ((static_branch_unlikely(&init_on_alloc) || static_branch_unlikely(&init_on_free)) && (slub_debug & SLAB_POISON)) _
