From: Breno Leitao <leitao@debian.org>
To: mst@redhat.com
Cc: mst@redhat.com, Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@kernel.org>,
david@kernel.org, Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>,
linux-mm@kvack.org, linux-next@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: BUG: mm: VM_BUG_ON_PAGE in post_alloc_hook() via __ClearPagePrezeroed() on compound pages
Date: Thu, 4 Jun 2026 03:59:06 -0700 [thread overview]
Message-ID: <aiFZeSKzb4HLfjFm@gmail.com> (raw)
Hi Michael,
Booting next-20260603 (a225caacc365) on arm64 with CONFIG_DEBUG_VM=y
panics in start_kernel() during kmem_cache_init():
page dumped because: VM_BUG_ON_PAGE(1 && PageCompound(page))
kernel BUG at ./include/linux/page-flags.h:682!
Internal error: Oops - BUG: 00000000f2000800 [#1] SMP
CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 7.1.0-rc6-next-20260603
Hardware name: linux,dummy-virt (DT)
pc : post_alloc_hook+0x224/0x2b8
Call trace:
post_alloc_hook+0x224/0x2b8 (P)
get_page_from_freelist+0x18a4/0x1b18
__alloc_frozen_pages_noprof+0x1b0/0x2068
__alloc_pages_mpol+0x130/0x2d0
alloc_frozen_pages_noprof+0x64/0xe8
alloc_slab_page+0x88/0x140
new_slab+0x11c/0x680
___slab_alloc+0x18c/0x7f0
__kmalloc_noprof+0x534/0x938
do_kmem_cache_create+0x724/0x890
create_boot_cache+0xc8/0x148
create_kmalloc_cache+0x5c/0xc8
new_kmalloc_cache+0x274/0x438
create_kmalloc_caches+0x2c/0x88
kmem_cache_init+0x228/0x2e0
mm_core_init+0x74/0xa0
start_kernel+0x1cc/0x4d0
Bisected (by inspection) to:
504f40f6bda6 ("mm: page_reporting: skip redundant zeroing of host-zeroed
reported pages")
Reproducer:
- linux-next 20260603, arm64 defconfig + DEBUG_VM=y (any debug-heavy
config will do; mine also has PROVE_LOCKING/DEBUG_LOCK_ALLOC, but
those are not required to trip the BUG once an order>0 __GFP_COMP
allocation hits prep_new_page).
- Boot under qemu-system-aarch64 -M virt with earlycon enabled.
I've tested something like the following and I was able to boot the host:
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -679,7 +679,7 @@ FOLIO_FLAG_FALSE(idle)
* PagePrezeroed() tracks pages known to be zero. The allocator
* uses this to skip redundant zeroing in post_alloc_hook().
*/
-__PAGEFLAG(Prezeroed, prezeroed, PF_NO_COMPOUND)
+__PAGEFLAG(Prezeroed, prezeroed, PF_ANY)
With that change the lockdep+DEBUG_VM kernel boots all the way through
SMP init and hands off to PID 1 on arm64.
Happy to test a follow-up patch if you'd prefer a different shape.
Thanks,
--breno
reply other threads:[~2026-06-04 10:59 UTC|newest]
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