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Tsirkin" , linux-kernel@vger.kernel.org, Huacai Chen Subject: [PATCH V4] mm/migrate: Fix NULL movable_ops if CONFIG_ZSMALLOC=m Date: Sun, 17 Aug 2025 23:17:59 +0800 Message-ID: <20250817151759.2525174-1-chenhuacai@loongson.cn> X-Mailer: git-send-email 2.47.3 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: qMiowJAx_8Gw8qForr9TAA--.35417S2 X-CM-SenderInfo: hfkh0x5xdftxo6or00hjvr0hdfq/ X-Coremail-Antispam: 1Uk129KBj93XoWxKF4xGF4kWFWrWF1fAr43Jwc_yoW3ZFy3pF 48Ar4UGr48JrW7JF17AF1UAry5Wws7uF4UJr9rGw1UZrn8Ww17GFyUtFy7Zr1rWr45JF17 JF1Dtw1Ykr4UJ3gCm3ZEXasCq-sJn29KB7ZKAUJUUUUf529EdanIXcx71UUUUU7KY7ZEXa sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU 0xBIdaVrnRJUUUBIb4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2 IYs7xG6rWj6s0DM7CIcVAFz4kK6r1Y6r17M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Gr0_Xr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI 0_Gr0_Cr1l84ACjcxK6I8E87Iv67AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVCY1x0267AK xVW8Jr0_Cr1UM2kKe7AKxVWUAVWUtwAS0I0E0xvYzxvE52x082IY62kv0487Mc804VCY07 AIYIkI8VC2zVCFFI0UMc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AKxVWU AVWUtwAv7VC2z280aVAFwI0_Gr0_Cr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0Y48IcxkI7V AKI48JMxkF7I0En4kS14v26r1q6r43MxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY 6r1j6r4UMxCIbckI1I0E14v26r126r1DMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7 xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCIc40Y0x0EwIxGrwCI42IY6xII jxv20xvE14v26r1I6r4UMIIF0xvE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwCI42IY6xAIw2 0EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Gr0_Cr1lIxAIcVC2z280aVCY1x02 67AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7IU8loGPUUUUU== Content-Type: text/plain; charset="utf-8" After commit 84caf98838a3e5f4bdb34 ("mm: stop storing migration_ops in page->mapping") we get such an error message if CONFIG_ZSMALLOC=3Dm: WARNING: CPU: 3 PID: 42 at mm/migrate.c:142 isolate_movable_ops_page+0xa8/= 0x1c0 CPU: 3 UID: 0 PID: 42 Comm: kcompactd0 Not tainted 6.16.0-rc5+ #2133 PREEM= PT pc 9000000000540bd8 ra 9000000000540b84 tp 9000000100420000 sp 90000001004= 23a60 a0 9000000100193a80 a1 000000000000000c a2 000000000000001b a3 fffffffffff= fffff a4 ffffffffffffffff a5 0000000000000267 a6 0000000000000000 a7 90000001004= 23ae0 t0 00000000000000f1 t1 00000000000000f6 t2 0000000000000000 t3 00000000000= 00001 t4 ffffff00010eb834 t5 0000000000000040 t6 900000010c89d380 t7 90000000023= fcc70 t8 0000000000000018 u0 0000000000000000 s9 ffffff00010eb800 s0 ffffff00010= eb800 s1 000000000000000c s2 0000000000043ae0 s3 0000800000000000 s4 90000000021= 9cc40 s5 0000000000000000 s6 ffffff00010eb800 s7 0000000000000001 s8 90000000025= b4000 ra: 9000000000540b84 isolate_movable_ops_page+0x54/0x1c0 ERA: 9000000000540bd8 isolate_movable_ops_page+0xa8/0x1c0 CRMD: 000000b0 (PLV0 -IE -DA +PG DACF=3DCC DACM=3DCC -WE) PRMD: 00000004 (PPLV0 +PIE -PWE) EUEN: 00000000 (-FPE -SXE -ASXE -BTE) ECFG: 00071c1d (LIE=3D0,2-4,10-12 VS=3D7) ESTAT: 000c0000 [BRK] (IS=3D ECode=3D12 EsubCode=3D0) PRID: 0014c010 (Loongson-64bit, Loongson-3A5000) CPU: 3 UID: 0 PID: 42 Comm: kcompactd0 Not tainted 6.16.0-rc5+ #2133 PREEM= PT Stack : 90000000021fd000 0000000000000000 9000000000247720 9000000100420000 90000001004236a0 90000001004236a8 0000000000000000 90000001004237e8 90000001004237e0 90000001004237e0 9000000100423550 0000000000000001 0000000000000001 90000001004236a8 725a84864a19e2d9 90000000023fcc58 9000000100420000 90000000024c6848 9000000002416848 0000000000000001 0000000000000000 000000000000000a 0000000007fe0000 ffffff00010eb800 0000000000000000 90000000021fd000 0000000000000000 900000000205cf30 000000000000008e 0000000000000009 ffffff00010eb800 0000000000000001 90000000025b4000 0000000000000000 900000000024773c 00007ffff103d748 00000000000000b0 0000000000000004 0000000000000000 0000000000071c1d ... Call Trace: [<900000000024773c>] show_stack+0x5c/0x190 [<90000000002415e0>] dump_stack_lvl+0x70/0x9c [<90000000004abe6c>] isolate_migratepages_block+0x3bc/0x16e0 [<90000000004af408>] compact_zone+0x558/0x1000 [<90000000004b0068>] compact_node+0xa8/0x1e0 [<90000000004b0aa4>] kcompactd+0x394/0x410 [<90000000002b3c98>] kthread+0x128/0x140 [<9000000001779148>] ret_from_kernel_thread+0x28/0xc0 [<9000000000245528>] ret_from_kernel_thread_asm+0x10/0x88 The reason is that defined(CONFIG_ZSMALLOC) evaluates to 1 only when CONFIG_ZSMALLOC=3Dy, we should use IS_ENABLED(CONFIG_ZSMALLOC) instead. But when I use IS_ENABLED(CONFIG_ZSMALLOC), page_movable_ops() cannot access zsmalloc_mops because zsmalloc_mops is in a module. To solve this problem, we define a set_movable_ops() interface to register and unregister offline_movable_ops / zsmalloc_movable_ops in mm/migrate.c, and call them at mm/balloon_compaction.c & mm/zsmalloc.c. Since offline_movable_ops / zsmalloc_movable_ops are always accessible, all #ifdef / #endif are removed in page_movable_ops(). Fixes: 84caf98838a3e5f ("mm: stop storing migration_ops in page->mapping") Acked-by: Zi Yan Signed-off-by: Huacai Chen Acked-by: David Hildenbrand --- V2: Use EXPORT_SYMBOL_GPL_FOR_MODULES instead of EXPORT_SYMBOL and fix buil= d. V3: Use register interface instead of set array directly (Thank David). V4: Update commit message for V3 changes and fix warning. include/linux/migrate.h | 5 +++++ mm/balloon_compaction.c | 6 ++++++ mm/migrate.c | 38 ++++++++++++++++++++++++++++++-------- mm/zsmalloc.c | 10 ++++++++++ 4 files changed, 51 insertions(+), 8 deletions(-) diff --git a/include/linux/migrate.h b/include/linux/migrate.h index acadd41e0b5c..9009e27b5f44 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -79,6 +79,7 @@ void migration_entry_wait_on_locked(swp_entry_t entry, sp= inlock_t *ptl) void folio_migrate_flags(struct folio *newfolio, struct folio *folio); int folio_migrate_mapping(struct address_space *mapping, struct folio *newfolio, struct folio *folio, int extra_count); +int set_movable_ops(const struct movable_operations *ops, enum pagetype ty= pe); =20 #else =20 @@ -100,6 +101,10 @@ static inline int migrate_huge_page_move_mapping(struc= t address_space *mapping, { return -ENOSYS; } +static inline int set_movable_ops(const struct movable_operations *ops, en= um pagetype type) +{ + return -ENOSYS; +} =20 #endif /* CONFIG_MIGRATION */ =20 diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c index 2a4a649805c1..03c5dbabb156 100644 --- a/mm/balloon_compaction.c +++ b/mm/balloon_compaction.c @@ -254,4 +254,10 @@ const struct movable_operations balloon_mops =3D { .putback_page =3D balloon_page_putback, }; =20 +static int __init balloon_init(void) +{ + return set_movable_ops(&balloon_mops, PGTY_offline); +} +core_initcall(balloon_init); + #endif /* CONFIG_BALLOON_COMPACTION */ diff --git a/mm/migrate.c b/mm/migrate.c index 425401b2d4e1..9e5ef39ce73a 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -43,8 +43,6 @@ #include #include #include -#include -#include =20 #include =20 @@ -53,6 +51,33 @@ #include "internal.h" #include "swap.h" =20 +static const struct movable_operations *offline_movable_ops; +static const struct movable_operations *zsmalloc_movable_ops; + +int set_movable_ops(const struct movable_operations *ops, enum pagetype ty= pe) +{ + /* + * We only allow for selected types and don't handle concurrent + * registration attempts yet. + */ + switch (type) { + case PGTY_offline: + if (offline_movable_ops && ops) + return -EBUSY; + offline_movable_ops =3D ops; + break; + case PGTY_zsmalloc: + if (zsmalloc_movable_ops && ops) + return -EBUSY; + zsmalloc_movable_ops =3D ops; + break; + default: + return -EINVAL; + } + return 0; +} +EXPORT_SYMBOL_GPL(set_movable_ops); + static const struct movable_operations *page_movable_ops(struct page *page) { VM_WARN_ON_ONCE_PAGE(!page_has_movable_ops(page), page); @@ -62,15 +87,12 @@ static const struct movable_operations *page_movable_op= s(struct page *page) * it as movable, the page type must be sticky until the page gets freed * back to the buddy. */ -#ifdef CONFIG_BALLOON_COMPACTION if (PageOffline(page)) /* Only balloon compaction sets PageOffline pages movable. */ - return &balloon_mops; -#endif /* CONFIG_BALLOON_COMPACTION */ -#if defined(CONFIG_ZSMALLOC) && defined(CONFIG_COMPACTION) + return offline_movable_ops; if (PageZsmalloc(page)) - return &zsmalloc_mops; -#endif /* defined(CONFIG_ZSMALLOC) && defined(CONFIG_COMPACTION) */ + return zsmalloc_movable_ops; + return NULL; } =20 diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c index 2c5e56a65354..6c574ab8abff 100644 --- a/mm/zsmalloc.c +++ b/mm/zsmalloc.c @@ -2246,8 +2246,15 @@ EXPORT_SYMBOL_GPL(zs_destroy_pool); =20 static int __init zs_init(void) { + int rc __maybe_unused; + #ifdef CONFIG_ZPOOL zpool_register_driver(&zs_zpool_driver); +#endif +#ifdef CONFIG_COMPACTION + rc =3D set_movable_ops(&zsmalloc_mops, PGTY_zsmalloc); + if (rc) + return rc; #endif zs_stat_init(); return 0; @@ -2257,6 +2264,9 @@ static void __exit zs_exit(void) { #ifdef CONFIG_ZPOOL zpool_unregister_driver(&zs_zpool_driver); +#endif +#ifdef CONFIG_COMPACTION + set_movable_ops(NULL, PGTY_zsmalloc); #endif zs_stat_exit(); } --=20 2.47.3