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Author SHA1 Message Date
Huacai Chen 97e5a55686 mm: remove the BOUNCE config option 
Commit eeadd68e2a5f ("block: remove bounce buffering support") remove
block/bounce.c but left the BOUNCE config option.  Now this option has no
users, so remove it.

Link: https://lkml.kernel.org/r/20251013095620.1111061-1-chenhuacai@loongson.cn
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Cc: John Garry <john.g.garry@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: maoxiaochuan <maoxiaochuan@loongson.cn>
 2026-02-04 16:39:55 +08:00
David Hildenbrand 12218dff44 mm: stop making SPARSEMEM_VMEMMAP user-selectable 
Patch series "mm: remove nth_page()", v2.

As discussed recently with Linus, nth_page() is just nasty and we would
like to remove it.

To recap, the reason we currently need nth_page() within a folio is
because on some kernel configs (SPARSEMEM without SPARSEMEM_VMEMMAP), the
memmap is allocated per memory section.

While buddy allocations cannot cross memory section boundaries, hugetlb
and dax folios can.

So crossing a memory section means that "page++" could do the wrong thing.
Instead, nth_page() on these problematic configs always goes from
page->pfn, to the go from (++pfn)->page, which is rather nasty.

Likely, many people have no idea when nth_page() is required and when it
might be dropped.

We refer to such problematic PFN ranges and "non-contiguous pages".  If we
only deal with "contiguous pages", there is not need for nth_page().

Besides that "obvious" folio case, we might end up using nth_page() within
CMA allocations (again, could span memory sections), and in one corner
case (kfence) when processing memblock allocations (again, could span
memory sections).

So let's handle all that, add sanity checks, and remove nth_page().

Patch #1 -> #5   : stop making SPARSEMEM_VMEMMAP user-selectable + cleanups
Patch #6 -> #13  : disallow folios to have non-contiguous pages
Patch #14 -> #20 : remove nth_page() usage within folios
Patch #22        : disallow CMA allocations of non-contiguous pages
Patch #23 -> #33 : sanity+check + remove nth_page() usage within SG entry
Patch #34        : sanity-check + remove nth_page() usage in
                   unpin_user_page_range_dirty_lock()
Patch #35        : remove nth_page() in kfence
Patch #36        : adjust stale comment regarding nth_page
Patch #37        : mm: remove nth_page()

A lot of this is inspired from the discussion at [1] between Linus, Jason
and me, so cudos to them.

This patch (of 37):

In an ideal world, we wouldn't have to deal with SPARSEMEM without
SPARSEMEM_VMEMMAP, but in particular for 32bit SPARSEMEM_VMEMMAP is
considered too costly and consequently not supported.

However, if an architecture does support SPARSEMEM with SPARSEMEM_VMEMMAP,
let's forbid the user to disable VMEMMAP: just like we already do for
arm64, s390 and x86.

So if SPARSEMEM_VMEMMAP is supported, don't allow to use SPARSEMEM without
SPARSEMEM_VMEMMAP.

This implies that the option to not use SPARSEMEM_VMEMMAP will now be gone
for loongarch, powerpc, riscv and sparc.  All architectures only enable
SPARSEMEM_VMEMMAP with 64bit support, so there should not really be a big
downside to using the VMEMMAP (quite the contrary).

This is a preparation for not supporting

(1) folio sizes that exceed a single memory section

(2) CMA allocations of non-contiguous page ranges

in SPARSEMEM without SPARSEMEM_VMEMMAP configs, whereby we want to limit
possible impact as much as possible (e.g., gigantic hugetlb page
allocations suddenly fails).

Link: https://lkml.kernel.org/r/20250901150359.867252-1-david@redhat.com
Link: https://lkml.kernel.org/r/20250901150359.867252-2-david@redhat.com
Link: https://lore.kernel.org/all/CAHk-=wiCYfNp4AJLBORU-c7ZyRBUp66W2-Et6cdQ4REx-GyQ_A@mail.gmail.com/T/#u [1]
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Alexandru Elisei <alexandru.elisei@arm.com>
Cc: Alex Dubov <oakad@yahoo.com>
Cc: Alex Willamson <alex.williamson@redhat.com>
Cc: Bart van Assche <bvanassche@acm.org>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Brett Creeley <brett.creeley@amd.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christoph Lameter (Ampere) <cl@gentwo.org>
Cc: Damien Le Maol <dlemoal@kernel.org>
Cc: Dave Airlie <airlied@gmail.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Doug Gilbert <dgilbert@interlog.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Inki Dae <m.szyprowski@samsung.com>
Cc: James Bottomley <james.bottomley@HansenPartnership.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Jason A. Donenfeld <jason@zx2c4.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>
Cc: Lars Persson <lars.persson@axis.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Marco Elver <elver@google.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Maxim Levitky <maximlevitsky@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Niklas Cassel <cassel@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Robin Murohy <robin.murphy@arm.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Tvrtko Ursulin <tursulin@ursulin.net>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Yishai Hadas <yishaih@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: maoxiaochuan <maoxiaochuan@loongson.cn>
 2026-02-04 16:39:52 +08:00
Huacai Chen c902e81162 LoongArch: Introduce the numa_memblks conversion 
Commit 87482708210ff3333a ("mm: introduce numa_memblks") has moved
numa_memblks from x86 to the generic code, but LoongArch was left out
of this conversion.

This patch introduces the generic numa_memblks for LoongArch.

In detail:
1. Enable NUMA_MEMBLKS (but disable NUMA_EMU) in Kconfig;
2. Use generic definition for numa_memblk and numa_meminfo;
3. Use generic implementation for numa_add_memblk() and its friends;
4. Use generic implementation for numa_set_distance() and its friends;
5. Use generic implementation for memory_add_physaddr_to_nid() and its
   friends.

Note: Disable NUMA_EMU because it needs more efforts and no obvious
demand now.

Tested-by: Binbin Zhou <zhoubinbin@loongson.cn>
Signed-off-by: Yuquan Wang <wangyuquan1236@phytium.com.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: maoxiaochuan <maoxiaochuan@loongson.cn>
 2025-11-10 08:55:28 +08:00
Tianyang Zhang da6b9e529a mm/page_alloc.c: avoid infinite retries caused by cpuset race 
__alloc_pages_slowpath has no change detection for ac->nodemask in the
part of retry path, while cpuset can modify it in parallel.  For some
processes that set mempolicy as MPOL_BIND, this results ac->nodemask
changes, and then the should_reclaim_retry will judge based on the latest
nodemask and jump to retry, while the get_page_from_freelist only
traverses the zonelist from ac->preferred_zoneref, which selected by a
expired nodemask and may cause infinite retries in some cases

cpu 64:
__alloc_pages_slowpath {
        /* ..... */
retry:
        /* ac->nodemask = 0x1, ac->preferred->zone->nid = 1 */
        if (alloc_flags & ALLOC_KSWAPD)
                wake_all_kswapds(order, gfp_mask, ac);
        /* cpu 1:
        cpuset_write_resmask
            update_nodemask
                update_nodemasks_hier
                    update_tasks_nodemask
                        mpol_rebind_task
                         mpol_rebind_policy
                          mpol_rebind_nodemask
		// mempolicy->nodes has been modified,
		// which ac->nodemask point to

        */
        /* ac->nodemask = 0x3, ac->preferred->zone->nid = 1 */
        if (should_reclaim_retry(gfp_mask, order, ac, alloc_flags,
                                 did_some_progress > 0, &no_progress_loops))
                goto retry;
}

Simultaneously starting multiple cpuset01 from LTP can quickly reproduce
this issue on a multi node server when the maximum memory pressure is
reached and the swap is enabled

Link: https://lkml.kernel.org/r/20250416082405.20988-1-zhangtianyang@loongson.cn
Fixes: c33d6c06f60f ("mm, page_alloc: avoid looking up the first zone in a zonelist twice")
Signed-off-by: Tianyang Zhang <zhangtianyang@loongson.cn>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Zi Yan <ziy@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: maoxiaochuan <maoxiaochuan@loongson.cn>
 2025-11-10 08:55:27 +08:00
maoxiaochuan 8b074cffbf init src (linux-6.12.0) 2025-02-13 14:11:16 +08:00