The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 3ee2d7471fa4963a2ced0a84f0653ce88b43c5b2 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023041141-negligent-sappy-dd84@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

3ee2d7471fa4 ("mm: kfence: fix PG_slab and memcg_data clearing") 8f0b36497303 ("mm: kfence: fix objcgs vector allocation") b33f778bba5e ("kfence: alloc kfence_pool after system startup") 698361bca2d5 ("kfence: allow re-enabling KFENCE after system startup") 07e8481d3c38 ("kfence: always use static branches to guard kfence_alloc()") 08f6b10630f2 ("kfence: limit currently covered allocations when pool nearly full") a9ab52bbcb52 ("kfence: move saving stack trace of allocations into __kfence_alloc()") 9a19aeb56650 ("kfence: count unexpectedly skipped allocations")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 3ee2d7471fa4963a2ced0a84f0653ce88b43c5b2 Mon Sep 17 00:00:00 2001 From: Muchun Song muchun.song@linux.dev Date: Mon, 20 Mar 2023 11:00:59 +0800 Subject: [PATCH] mm: kfence: fix PG_slab and memcg_data clearing

It does not reset PG_slab and memcg_data when KFENCE fails to initialize kfence pool at runtime. It is reporting a "Bad page state" message when kfence pool is freed to buddy. The checking of whether it is a compound head page seems unnecessary since we already guarantee this when allocating kfence pool. Remove the check to simplify the code.

Link: https://lkml.kernel.org/r/20230320030059.20189-1-songmuchun@bytedance.com Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure") Signed-off-by: Muchun Song songmuchun@bytedance.com Cc: Alexander Potapenko glider@google.com Cc: Dmitry Vyukov dvyukov@google.com Cc: Jann Horn jannh@google.com Cc: Marco Elver elver@google.com Cc: Roman Gushchin roman.gushchin@linux.dev Cc: SeongJae Park sjpark@amazon.de Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org

diff --git a/mm/kfence/core.c b/mm/kfence/core.c index 79c94ee55f97..d66092dd187c 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -561,10 +561,6 @@ static unsigned long kfence_init_pool(void) if (!i || (i % 2)) continue;

- /* Verify we do not have a compound head page. */ - if (WARN_ON(compound_head(&pages[i]) != &pages[i])) - return addr; - __folio_set_slab(slab_folio(slab)); #ifdef CONFIG_MEMCG slab->memcg_data = (unsigned long)&kfence_metadata[i / 2 - 1].objcg | @@ -597,12 +593,26 @@ static unsigned long kfence_init_pool(void)

/* Protect the right redzone. */ if (unlikely(!kfence_protect(addr + PAGE_SIZE))) - return addr; + goto reset_slab;

addr += 2 * PAGE_SIZE; }

return 0; + +reset_slab: + for (i = 0; i < KFENCE_POOL_SIZE / PAGE_SIZE; i++) { + struct slab *slab = page_slab(&pages[i]); + + if (!i || (i % 2)) + continue; +#ifdef CONFIG_MEMCG + slab->memcg_data = 0; +#endif + __folio_clear_slab(slab_folio(slab)); + } + + return addr; }

static bool __init kfence_init_pool_early(void) @@ -632,16 +642,6 @@ static bool __init kfence_init_pool_early(void) * fails for the first page, and therefore expect addr==__kfence_pool in * most failure cases. */ - for (char *p = (char *)addr; p < __kfence_pool + KFENCE_POOL_SIZE; p += PAGE_SIZE) { - struct slab *slab = virt_to_slab(p); - - if (!slab) - continue; -#ifdef CONFIG_MEMCG - slab->memcg_data = 0; -#endif - __folio_clear_slab(slab_folio(slab)); - } memblock_free_late(__pa(addr), KFENCE_POOL_SIZE - (addr - (unsigned long)__kfence_pool)); __kfence_pool = NULL; return false;