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+0200, Vlastimil Babka wrote: > We touch slab->freelist and slab->inuse before checking the slab pointer > is actually sane. Do that validation first, which will be safer. We can > thus also remove the check from alloc_debug_processing(). > > This adds a new "s->flags & SLAB_CONSISTENCY_CHECKS" test but > alloc_single_from_partial() is only called for caches with debugging > enabled so it's acceptable. > > In alloc_single_from_new_slab() we just created the struct slab and call > alloc_debug_processing() to mainly set up redzones, tracking etc, while > not really expecting the consistency checks to fail. Thus don't validate > it there. > > Signed-off-by: Vlastimil Babka > --- > mm/slub.c | 20 ++++++++++++-------- > 1 file changed, 12 insertions(+), 8 deletions(-) > > diff --git a/mm/slub.c b/mm/slub.c > index 12ad42f3d2e066b02340f2c30a85422583af3c5d..e5b53d1debddd3fe0f941f579a1043a5b976e50b 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -821,6 +821,8 @@ static inline unsigned int get_orig_size(struct kmem_cache *s, void *object) > return *(unsigned int *)p; > } > > +#ifdef CONFIG_SLUB_DEBUG > + > /* > * For debugging context when we want to check if the struct slab pointer > * appears to be valid. > @@ -830,7 +832,6 @@ static inline bool validate_slab_ptr(struct slab *slab) > return PageSlab(slab_page(slab)); > } > > -#ifdef CONFIG_SLUB_DEBUG > static unsigned long object_map[BITS_TO_LONGS(MAX_OBJS_PER_PAGE)]; > static DEFINE_SPINLOCK(object_map_lock); > > @@ -1651,11 +1652,6 @@ static noinline bool alloc_debug_processing(struct kmem_cache *s, > struct slab *slab, void *object, int orig_size) > { > if (s->flags & SLAB_CONSISTENCY_CHECKS) { > - if (!validate_slab_ptr(slab)) { > - slab_err(s, slab, "Not a valid slab page"); > - return false; > - } > - > if (!alloc_consistency_checks(s, slab, object)) > goto bad; > } > @@ -2825,13 +2821,21 @@ static void *alloc_single_from_partial(struct kmem_cache *s, > > lockdep_assert_held(&n->list_lock); > > +#ifdef SLUB_DEBUG I'm sure you meant CONFIG_SLUB_DEBUG ;) With that adjusted, looks good to me, Reviewed-by: Harry Yoo > + if (s->flags & SLAB_CONSISTENCY_CHECKS) { > + if (!validate_slab_ptr(slab)) { > + slab_err(s, slab, "Not a valid slab page"); > + return NULL; > + } > + } > +#endif > + > object = slab->freelist; > slab->freelist = get_freepointer(s, object); > slab->inuse++; > > if (!alloc_debug_processing(s, slab, object, orig_size)) { > - if (validate_slab_ptr(slab)) > - remove_partial(n, slab); > + remove_partial(n, slab); > return NULL; > } -- Cheers, Harry / Hyeonggon