mm/slub: free KFENCE objects in slab_free_hook()

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When freeing an object that was allocated from KFENCE, we do that in the
slowpath __slab_free(), relying on the fact that KFENCE "slab" cannot be
the cpu slab, so the fastpath has to fallback to the slowpath.

This optimization doesn't help much though, because is_kfence_address()
is checked earlier anyway during the free hook processing or detached
freelist building. Thus we can simplify the code by making the
slab_free_hook() free the KFENCE object immediately, similarly to KASAN
quarantine.

In slab_free_hook() we can place kfence_free() above init processing, as
callers have been making sure to set init to false for KFENCE objects.
This simplifies slab_free(). This places it also above kasan_slab_free()
which is ok as that skips KFENCE objects anyway.

While at it also determine the init value in slab_free_freelist_hook()
outside of the loop.

This change will also make introducing per cpu array caches easier.

Tested-by: Marco Elver <elver@google.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

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This commit is contained in:

Vlastimil Babka 2023-11-14 22:12:47 +01:00

parent 284f17ac13

commit 782f8906f8

1 changed files with 10 additions and 12 deletions

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mm/slub.c

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