From: "Michael S. Tsirkin" <mst@redhat.com>
To: Breno Leitao <leitao@debian.org>
Cc: 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: Re: BUG: mm: VM_BUG_ON_PAGE in post_alloc_hook() via __ClearPagePrezeroed() on compound pages
Date: Thu, 4 Jun 2026 19:05:42 -0400 [thread overview]
Message-ID: <20260604190521-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <aiFZeSKzb4HLfjFm@gmail.com>
On Thu, Jun 04, 2026 at 03:59:06AM -0700, Breno Leitao wrote:
> Hi Michael,
>
> Booting next-20260603 (a225caacc365) on arm64 with CONFIG_DEBUG_VM=y
> panics in start_kernel() during kmem_cache_init():
it's my bad i pushed a wrong branch to next. Sorry.
> 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
prev parent reply other threads:[~2026-06-04 23:05 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-04 10:59 BUG: mm: VM_BUG_ON_PAGE in post_alloc_hook() via __ClearPagePrezeroed() on compound pages Breno Leitao
2026-06-04 23:05 ` Michael S. Tsirkin [this message]
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