linux-kernel - Re: [PATCH V5 mm-hotfixes 3/3] x86/mm/64: define ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <61cd1dfd-f51c-4f47-84d2-1f8b134105e4@redhat.com>
Date: Mon, 18 Aug 2025 09:49:30 +0200
From: David Hildenbrand <david@...hat.com>
To: Harry Yoo <harry.yoo@...cle.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
 Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
 Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>,
 "H . Peter Anvin" <hpa@...cr.com>
Cc: Andrey Ryabinin <ryabinin.a.a@...il.com>, Arnd Bergmann <arnd@...db.de>,
 Dennis Zhou <dennis@...nel.org>, Tejun Heo <tj@...nel.org>,
 Christoph Lameter <cl@...two.org>, Alexander Potapenko <glider@...gle.com>,
 Andrey Konovalov <andreyknvl@...il.com>, Dmitry Vyukov <dvyukov@...gle.com>,
 Vincenzo Frascino <vincenzo.frascino@....com>, Juergen Gross
 <jgross@...e.de>, Kevin Brodsky <kevin.brodsky@....com>,
 Oscar Salvador <osalvador@...e.de>, Joao Martins
 <joao.m.martins@...cle.com>, Lorenzo Sccakes <lorenzo.stoakes@...cle.com>,
 Jane Chu <jane.chu@...cle.com>, Alistair Popple <apopple@...dia.com>,
 Mike Rapoport <rppt@...nel.org>, Gwan-gyeong Mun
 <gwan-gyeong.mun@...el.com>, "Aneesh Kumar K . V"
 <aneesh.kumar@...ux.ibm.com>, Uladzislau Rezki <urezki@...il.com>,
 "Liam R . Howlett" <Liam.Howlett@...cle.com>,
 Vlastimil Babka <vbabka@...e.cz>, Suren Baghdasaryan <surenb@...gle.com>,
 Michal Hocko <mhocko@...e.com>, Qi Zheng <zhengqi.arch@...edance.com>,
 Ard Biesheuvel <ardb@...nel.org>, Thomas Huth <thuth@...hat.com>,
 John Hubbard <jhubbard@...dia.com>, Ryan Roberts <ryan.roberts@....com>,
 Peter Xu <peterx@...hat.com>, Dev Jain <dev.jain@....com>,
 Bibo Mao <maobibo@...ngson.cn>, Anshuman Khandual
 <anshuman.khandual@....com>, Joerg Roedel <joro@...tes.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
 linux-mm@...ck.org, stable@...r.kernel.org, Kiryl Shutsemau <kas@...nel.org>
Subject: Re: [PATCH V5 mm-hotfixes 3/3] x86/mm/64: define
 ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings()

On 18.08.25 04:02, Harry Yoo wrote:
> Define ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings() to ensure
> page tables are properly synchronized when calling
> p*d_populate_kernel().
> 
> For 5-level paging, synchronization is performed via
> pgd_populate_kernel(). In 4-level paging, pgd_populate() is a no-op,
> so synchronization is instead performed at the P4D level via
> p4d_populate_kernel().
> 
> This fixes intermittent boot failures on systems using 4-level paging
> and a large amount of persistent memory:
> 
>    BUG: unable to handle page fault for address: ffffe70000000034
>    #PF: supervisor write access in kernel mode
>    #PF: error_code(0x0002) - not-present page
>    PGD 0 P4D 0
>    Oops: 0002 [#1] SMP NOPTI
>    RIP: 0010:__init_single_page+0x9/0x6d
>    Call Trace:
>     <TASK>
>     __init_zone_device_page+0x17/0x5d
>     memmap_init_zone_device+0x154/0x1bb
>     pagemap_range+0x2e0/0x40f
>     memremap_pages+0x10b/0x2f0
>     devm_memremap_pages+0x1e/0x60
>     dev_dax_probe+0xce/0x2ec [device_dax]
>     dax_bus_probe+0x6d/0xc9
>     [... snip ...]
>     </TASK>
> 
> It also fixes a crash in vmemmap_set_pmd() caused by accessing vmemmap
> before sync_global_pgds() [1]:
> 
>    BUG: unable to handle page fault for address: ffffeb3ff1200000
>    #PF: supervisor write access in kernel mode
>    #PF: error_code(0x0002) - not-present page
>    PGD 0 P4D 0
>    Oops: Oops: 0002 [#1] PREEMPT SMP NOPTI
>    Tainted: [W]=WARN
>    RIP: 0010:vmemmap_set_pmd+0xff/0x230
>     <TASK>
>     vmemmap_populate_hugepages+0x176/0x180
>     vmemmap_populate+0x34/0x80
>     __populate_section_memmap+0x41/0x90
>     sparse_add_section+0x121/0x3e0
>     __add_pages+0xba/0x150
>     add_pages+0x1d/0x70
>     memremap_pages+0x3dc/0x810
>     devm_memremap_pages+0x1c/0x60
>     xe_devm_add+0x8b/0x100 [xe]
>     xe_tile_init_noalloc+0x6a/0x70 [xe]
>     xe_device_probe+0x48c/0x740 [xe]
>     [... snip ...]
> 
> Cc: <stable@...r.kernel.org>
> Fixes: 8d400913c231 ("x86/vmemmap: handle unpopulated sub-pmd ranges")
> Closes: https://lore.kernel.org/linux-mm/20250311114420.240341-1-gwan-gyeong.mun@intel.com [1]
> Suggested-by: Dave Hansen <dave.hansen@...ux.intel.com>
> Acked-by: Kiryl Shutsemau <kas@...nel.org>
> Reviewed-by: Mike Rapoport (Microsoft) <rppt@...nel.org>
> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
> Signed-off-by: Harry Yoo <harry.yoo@...cle.com>
> ---

Acked-by: David Hildenbrand <david@...hat.com>

-- 
Cheers

David / dhildenb