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Ge Yang f415148282 mm/hugetlb: wait for hugetlb folios to be freed 
[ Upstream commit 67bab13307 ]

Since the introduction of commit c77c0a8ac4 ("mm/hugetlb: defer freeing
of huge pages if in non-task context"), which supports deferring the
freeing of hugetlb pages, the allocation of contiguous memory through
cma_alloc() may fail probabilistically.

In the CMA allocation process, if it is found that the CMA area is
occupied by in-use hugetlb folios, these in-use hugetlb folios need to be
migrated to another location.  When there are no available hugetlb folios
in the free hugetlb pool during the migration of in-use hugetlb folios,
new folios are allocated from the buddy system.  A temporary state is set
on the newly allocated folio.  Upon completion of the hugetlb folio
migration, the temporary state is transferred from the new folios to the
old folios.  Normally, when the old folios with the temporary state are
freed, it is directly released back to the buddy system.  However, due to
the deferred freeing of hugetlb pages, the PageBuddy() check fails,
ultimately leading to the failure of cma_alloc().

Here is a simplified call trace illustrating the process:
cma_alloc()
    ->__alloc_contig_migrate_range() // Migrate in-use hugetlb folios
        ->unmap_and_move_huge_page()
            ->folio_putback_hugetlb() // Free old folios
    ->test_pages_isolated()
        ->__test_page_isolated_in_pageblock()
             ->PageBuddy(page) // Check if the page is in buddy

To resolve this issue, we have implemented a function named
wait_for_freed_hugetlb_folios().  This function ensures that the hugetlb
folios are properly released back to the buddy system after their
migration is completed.  By invoking wait_for_freed_hugetlb_folios()
before calling PageBuddy(), we ensure that PageBuddy() will succeed.

Link: https://lkml.kernel.org/r/1739936804-18199-1-git-send-email-yangge1116@126.com
Fixes: c77c0a8ac4 ("mm/hugetlb: defer freeing of huge pages if in non-task context")
Signed-off-by: Ge Yang <yangge1116@126.com>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <21cnbao@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2025-03-22 12:54:28 -07:00
arch x86/vmware: Parse MP tables for SEV-SNP enabled guests under VMware hypervisors 2025-03-22 12:54:27 -07:00
block block: fix 'kmem_cache of name 'bio-108' already exists' 2025-03-22 12:54:21 -07:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: api - Fix boot-up self-test race 2025-02-08 09:57:28 +01:00
Documentation rust: remove leftover mentions of the alloc crate 2025-03-22 12:54:23 -07:00
drivers i2c: sis630: Fix an error handling path in sis630_probe() 2025-03-22 12:54:27 -07:00
fs cifs: Fix integer overflow while processing closetimeo mount option 2025-03-22 12:54:27 -07:00
include mm/hugetlb: wait for hugetlb folios to be freed 2025-03-22 12:54:28 -07:00
init rust: Disallow BTF generation with Rust + LTO 2025-03-22 12:54:23 -07:00
io_uring io-wq: backoff when retrying worker creation 2025-03-22 12:54:19 -07:00
ipc ipc: fix memleak if msg_init_ns failed in create_ipc_ns 2024-12-05 14:03:02 +01:00
kernel sched_ext: Validate prev_cpu in scx_bpf_select_cpu_dfl() 2025-03-22 12:54:25 -07:00
lib rcuref: Plug slowpath race in rcuref_put() 2025-03-07 18:25:43 +01:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm mm/hugetlb: wait for hugetlb folios to be freed 2025-03-22 12:54:28 -07:00
net netmem: prevent TX of unreadable skbs 2025-03-22 12:54:25 -07:00
rust rust: init: add missing newline to pr_info! calls 2025-03-22 12:54:26 -07:00
samples rust: treewide: switch to the kernel Vec type 2025-03-13 13:01:46 +01:00
scripts scripts: generate_rust_analyzer: add uapi crate 2025-03-22 12:54:27 -07:00
security ima: Reset IMA_NONACTION_RULE_FLAGS after post_setattr 2025-03-07 18:25:44 +01:00
sound ASoC: codecs: wm0010: Fix error handling path in wm0010_spi_probe() 2025-03-22 12:54:26 -07:00
tools ASoC: dapm-graph: set fill colour of turned on nodes 2025-03-22 12:54:20 -07:00
usr kbuild: hdrcheck: fix cross build with clang 2025-03-13 13:02:18 +01:00
virt KVM: x86: switch hugepage recovery thread to vhost_task 2024-12-05 14:02:43 +01:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.clippy.toml rust: enable Clippy's check-private-items 2025-03-13 13:01:42 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore rust: introduce .clippy.toml 2025-03-13 13:01:42 +01:00
.mailmap mailmap: add entry for Thorsten Blum 2024-11-07 14:14:59 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove self from DSA entry 2024-11-03 12:52:38 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: add entry for the Rust alloc module 2025-03-13 13:01:47 +01:00
Makefile Linux 6.12.19 2025-03-13 13:02:20 +01:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.