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 1A8D95B5AB; Thu, 25 Jun 2026 00:54:58 +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=1782348900; cv=none; b=H8ROTJL7RXdOYY3hD+gB6TRhn0dpi4B1bcgGKIV14iOpUDkA6XWIXAgc8Fz6fvahB/jnAuW4bM1D0tldgJ/NS2CERqEfrwmHwi1Omf66woSvlGbJSz0E+yntmHoLpzWHKxsLq3Z6gvo5JQF+2JL6OJzYQctssdYkW46EGuaHxBg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782348900; c=relaxed/simple; bh=E1QMaLPuXJSmKrpKJ2S/oQ2jD77yOLsebWrvZbksCLQ=; h=Date:To:From:Subject:Message-Id; b=iNZONzT7lxYEv0OBwu6emgIKy4CCZV2r7aKPDDy9BOsyopDOF7Fw/ZksJg+RYJSWeH4qEkQGgq0Es2Qx1xj5jdX57hV8GmEOBmF8t88deenjkLaO7g4lyO3POOlWRRDg/m00Fy3FREEz9RmpkW0bQk1nK6wtTiPoCd7NL1Ullf4= 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=vTIQaQRZ; 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="vTIQaQRZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9F75F1F000E9; Thu, 25 Jun 2026 00:54:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1782348898; bh=rPJlVCmVLEVN7l0Dkkg76TNEEyp3cE7p52OjSBpRNJs=; h=Date:To:From:Subject; b=vTIQaQRZrmpZ012qLOlpnG2/oJ+5HT++vLF4ZQkZNPDFLss9HRalgrPnxkYoYo7oL TMT0bon7huwYOPa59Z6MEDR/zreUS+Ct/iuYfUjBLEsoXc0+37FCfBOvJUioD0r+Fh hP0wTqwY76J7Uha/A6vbzaLh2ZQxrEmvvogdHoFY= Date: Wed, 24 Jun 2026 17:54:58 -0700 To: mm-commits@vger.kernel.org,vbabka@kernel.org,stable@vger.kernel.org,osalvador@suse.de,muchun.song@linux.dev,kas@kernel.org,david@kernel.org,mclapinski@google.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-hugetlb-init-tails-before-init_migratetype.patch added to mm-hotfixes-unstable branch Message-Id: <20260625005458.9F75F1F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/hugetlb: init tails before init_migratetype has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-hugetlb-init-tails-before-init_migratetype.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-hugetlb-init-tails-before-init_migratetype.patch This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: Michal Clapinski Subject: mm/hugetlb: init tails before init_migratetype Date: Mon, 22 Jun 2026 12:19:01 +0200 Currently, if you enable HVO, DEFERRED_STRUCT_PAGE_INIT and VM_DEBUG the kernel will crash with the following stack trace get_pfnblock_bitmap_bitidx __set_pfnblock_flags_mask hugetlb_bootmem_init_migratetype prep_and_add_bootmem_folios gather_bootmem_prealloc_node gather_bootmem_prealloc_parallel padata_do_multithreaded gather_bootmem_prealloc hugetlb_init on this code VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page); This code looks inside the struct page which will be uninitialized for hugetlb tail pages, which will cause a false positive. So let's initialize the tail pages before this happens. Link: https://lore.kernel.org/20260622101901.223961-1-mclapinski@google.com Fixes: 622026e87c40 ("mm/hugetlb: remove fake head pages") Signed-off-by: Michal Clapinski Reviewed-by: Kiryl Shutsemau (Meta) Tested-by: Kiryl Shutsemau (Meta) Cc: David Hildenbrand Cc: Michal Clapinski Cc: Muchun Song Cc: Oscar Salvador Cc: Vlastimil Babka Cc: Signed-off-by: Andrew Morton --- mm/hugetlb.c | 1 + mm/hugetlb_vmemmap.c | 14 +++++++++----- mm/hugetlb_vmemmap.h | 5 +++++ 3 files changed, 15 insertions(+), 5 deletions(-) --- a/mm/hugetlb.c~mm-hugetlb-init-tails-before-init_migratetype +++ a/mm/hugetlb.c @@ -4127,6 +4127,7 @@ static int __init hugetlb_init(void) } hugetlb_init_hstates(); + hugetlb_vmemmap_init_tails(); gather_bootmem_prealloc(); report_hugepages(); --- a/mm/hugetlb_vmemmap.c~mm-hugetlb-init-tails-before-init_migratetype +++ a/mm/hugetlb_vmemmap.c @@ -867,14 +867,10 @@ static const struct ctl_table hugetlb_vm }, }; -static int __init hugetlb_vmemmap_init(void) +void __init hugetlb_vmemmap_init_tails(void) { - const struct hstate *h; struct zone *zone; - /* HUGETLB_VMEMMAP_RESERVE_SIZE should cover all used struct pages */ - BUILD_BUG_ON(__NR_USED_SUBPAGE > HUGETLB_VMEMMAP_RESERVE_PAGES); - for_each_zone(zone) { for (int i = 0; i < NR_VMEMMAP_TAILS; i++) { struct page *tail, *p; @@ -890,6 +886,14 @@ static int __init hugetlb_vmemmap_init(v init_compound_tail(p + j, NULL, order, zone); } } +} + +static int __init hugetlb_vmemmap_init(void) +{ + const struct hstate *h; + + /* HUGETLB_VMEMMAP_RESERVE_SIZE should cover all used struct pages */ + BUILD_BUG_ON(__NR_USED_SUBPAGE > HUGETLB_VMEMMAP_RESERVE_PAGES); for_each_hstate(h) { if (hugetlb_vmemmap_optimizable(h)) { --- a/mm/hugetlb_vmemmap.h~mm-hugetlb-init-tails-before-init_migratetype +++ a/mm/hugetlb_vmemmap.h @@ -20,6 +20,7 @@ #define HUGETLB_VMEMMAP_RESERVE_PAGES (HUGETLB_VMEMMAP_RESERVE_SIZE / sizeof(struct page)) #ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP +void hugetlb_vmemmap_init_tails(void); int hugetlb_vmemmap_restore_folio(const struct hstate *h, struct folio *folio); long hugetlb_vmemmap_restore_folios(const struct hstate *h, struct list_head *folio_list, @@ -72,6 +73,10 @@ static inline void hugetlb_vmemmap_optim { } +static inline void hugetlb_vmemmap_init_tails(void) +{ +} + static inline void hugetlb_vmemmap_optimize_bootmem_folios(struct hstate *h, struct list_head *folio_list) { _ Patches currently in -mm which might be from mclapinski@google.com are mm-hugetlb-init-tails-before-init_migratetype.patch