From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 277EF385D71; Thu, 9 Jul 2026 22:49:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783637396; cv=none; b=VhkZxpkUbYlkswywQRUtNQo3mHyh+VzKTjq+ZUDi0AQDQ+r8+S2ScCQNAj9EU1PKE/w6+eOmgTJDjoO2HVklHg1qqCGO4ERngJhZ2nRUcCDRDcL9mUFwR8un8H/4In4k6pqKEhbKx41ObQPzK4uwBb/xTn0eDIV5nQ9bLM1jgsM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783637396; c=relaxed/simple; bh=5yknw9e9aQ6pLOFteDO8pasGmD5vSTpAWoZl+pj8kUA=; h=Date:To:From:Subject:Message-Id; b=ClIrfMcuvSiVOuW+6uCbzXotoiHBIu93sfJAqb5YIVctr4h+4cApCz7iA+WQa59HXBY5ELf8bVkdA1GTIqwr+yOLiCfCXHdKMH8RZZuca0yWdxZZtAMWqH0n+D0mcSbn/4aNUzGsbx6rxEXzW8Wv1GZRHWOQ+fm/lde3JYh+fKU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=cMsqjdiq; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="cMsqjdiq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BA3F41F000E9; Thu, 9 Jul 2026 22:49:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1783637394; bh=zZeANOfNamqNh/8IHZcgS5mxJmoi6gOCUziTKaJq5RQ=; h=Date:To:From:Subject; b=cMsqjdiqW5IFVx3TccIp4GtsEmV8e0yXwb7ujbTr6snw+Cy2nGnzlhWBMHC2GShqZ AcjVBiWQs4HCSF2Y340rRskM0YsuDTt0Z9/y7mEFUiRCE+N9r0N7hCfUdphsore4HZ l7nhqjP0IBj3+fHnWQwnjYmE5BCWz19CiPdYCGCc= Date: Thu, 09 Jul 2026 15:49:54 -0700 To: mm-commits@vger.kernel.org,ziy@nvidia.com,yang@os.amperecomputing.com,stable@vger.kernel.org,ryan.roberts@arm.com,npache@redhat.com,ljs@kernel.org,liam@infradead.org,lance.yang@linux.dev,dev.jain@arm.com,david@kernel.org,baolin.wang@linux.alibaba.com,baohua@kernel.org,riel@surriel.com,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-hotfixes-stable] mm-huge_memory-set-pg_has_hwpoisoned-only-after-new-folio-head-is-established.patch removed from -mm tree Message-Id: <20260709224954.BA3F41F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm/huge_memory: set PG_has_hwpoisoned only after new folio head is established has been removed from the -mm tree. Its filename was mm-huge_memory-set-pg_has_hwpoisoned-only-after-new-folio-head-is-established.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Rik van Riel Subject: mm/huge_memory: set PG_has_hwpoisoned only after new folio head is established Date: Wed, 1 Jul 2026 13:42:34 -0400 __split_folio_to_order() copies the hwpoison state onto each new sub-folio while splitting a folio to a non-zero order. It does so via if (handle_hwpoison && page_range_has_hwpoisoned(new_head, new_nr_pages)) folio_set_has_hwpoisoned(new_folio); *before* clear_compound_head(new_head)/prep_compound_page(new_head, ...) turns @new_head from a tail page into a proper folio head. PG_has_hwpoisoned is a FOLIO_SECOND_PAGE flag, so folio_set_has_hwpoisoned() resolves to folio_flags(folio, 1). With the new compound_info-based page-flags layout, folio_flags() asserts the page is not a tail: VM_BUG_ON_PGFLAGS(page->compound_info & 1, page); VM_BUG_ON_PGFLAGS(n > 0 && !test_bit(PG_head, &page->flags.f), page); At the current call site @new_head still has the tail marker (compound_info bit 0 set, PG_head clear), so on CONFIG_DEBUG_VM kernels this hits: kernel BUG at include/linux/page-flags.h:354 folio_flags+0x82 folio_set_has_hwpoisoned __split_folio_to_order __split_unmapped_folio __folio_split truncate_inode_partial_folio (shmem hole-punch / MADV_REMOVE) Reproduced by syzkaller: hwpoison-inject a few subpages of a large shmem folio, then MADV_REMOVE (fallocate punch hole) on the same range, which splits the partial folio to a non-zero order. memory_failure() tries to split the poisoned folio to order 0 first, but that split is best-effort; when it fails the folio is left large with PG_has_hwpoisoned set, the case fa5a06170036 added this hwpoison copying for. Move the folio_set_has_hwpoisoned() call to after clear_compound_head()/prep_compound_page(), where @new_folio is a real order-new_order head folio (handle_hwpoison implies new_order != 0, so a second page always exists). The flag still lands on the same struct page (page[1] of the new folio); only the ordering relative to compound-head setup changes, satisfying the FOLIO_SECOND_PAGE precondition. Link: https://lore.kernel.org/20260701174235.3173401-1-riel@surriel.com Fixes: fa5a06170036 ("mm/huge_memory: preserve PG_has_hwpoisoned if a folio is split to >0 order") Signed-off-by: Rik van Riel Assisted-by: Claude:claude-opus-4-8 Reviewed-by: Zi Yan Acked-by: David Hildenbrand (Arm) Tested-by: Lance Yang Reviewed-by: Lorenzo Stoakes Reviewed-by: Baolin Wang Cc: Barry Song Cc: Dev Jain Cc: Lance Yang Cc: Liam R. Howlett Cc: Nico Pache Cc: Ryan Roberts Cc: Yang Shi Cc: Signed-off-by: Andrew Morton --- mm/huge_memory.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) --- a/mm/huge_memory.c~mm-huge_memory-set-pg_has_hwpoisoned-only-after-new-folio-head-is-established +++ a/mm/huge_memory.c @@ -3587,10 +3587,6 @@ static void __split_folio_to_order(struc (1L << PG_dropbehind) | LRU_GEN_MASK | LRU_REFS_MASK)); - if (handle_hwpoison && - page_range_has_hwpoisoned(new_head, new_nr_pages)) - folio_set_has_hwpoisoned(new_folio); - new_folio->mapping = folio->mapping; new_folio->index = folio->index + i; @@ -3612,6 +3608,14 @@ static void __split_folio_to_order(struc folio_set_large_rmappable(new_folio); } + /* + * PG_has_hwpoisoned is on the 2nd page, so set it after + * the compound head is prepped. + */ + if (handle_hwpoison && + page_range_has_hwpoisoned(new_head, new_nr_pages)) + folio_set_has_hwpoisoned(new_folio); + if (folio_test_young(folio)) folio_set_young(new_folio); if (folio_test_idle(folio)) _ Patches currently in -mm which might be from riel@surriel.com are