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DKIM_TRACE(0.00)[suse.cz:+] X-Spam-Score: -4.51 On 10/14/25 10:40, Vlastimil Babka wrote: > defer_free() links pending objects using the slab's freelist offset > which is fine as they are not free yet. free_deferred_objects() then > clears this pointer to avoid confusing the debugging consistency checks > that may be enabled for the cache. > > However, with CONFIG_SLAB_FREELIST_HARDENED, even the NULL pointer needs > to be encoded appropriately using set_freepointer(), otherwise it's > decoded as something else and triggers the consistency checks, as found > by the kernel test robot. > > Use set_freepointer() to prevent the issue. > > Fixes: af92793e52c3 ("slab: Introduce kmalloc_nolock() and kfree_nolock().") > Reported-by: kernel test robot > Closes: https://lore.kernel.org/oe-lkp/202510101652.7921fdc6-lkp@intel.com > Acked-by: Alexei Starovoitov > Signed-off-by: Vlastimil Babka > --- > will be added to slab/for-next-fixes and sent later this week > --- > mm/slub.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/mm/slub.c b/mm/slub.c > index b1f15598fbfd..64c17afc375b 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -6443,15 +6443,16 @@ static void free_deferred_objects(struct irq_work *work) > slab = virt_to_slab(x); > s = slab->slab_cache; > > + extra newline moved... > + /* Point 'x' back to the beginning of allocated object */ > + x -= s->offset; ... here. noticed and fixed up locally after sending... > /* > * We used freepointer in 'x' to link 'x' into df->objects. > * Clear it to NULL to avoid false positive detection > * of "Freepointer corruption". > */ > - *(void **)x = NULL; > + set_freepointer(s, x, NULL); > > - /* Point 'x' back to the beginning of allocated object */ > - x -= s->offset; > __slab_free(s, slab, x, x, 1, _THIS_IP_); > } > > > --- > base-commit: 3a8660878839faadb4f1a6dd72c3179c1df56787 > change-id: 20251014-fix-freelist-29915edcc2f4 > > Best regards,