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Jinjiang Tu 9342bc134a mm/memory_hotplug: fix call folio_test_large with tail page in do_migrate_range
We triggered the below BUG:

 page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x2 pfn:0x240402
 head: order:9 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
 flags: 0x1ffffe0000000040(head|node=1|zone=3|lastcpupid=0x1ffff)
 page_type: f4(hugetlb)
 page dumped because: VM_BUG_ON_PAGE(page->compound_head & 1)
 ------------[ cut here ]------------
 kernel BUG at ./include/linux/page-flags.h:310!
 Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP
 Modules linked in:
 CPU: 7 UID: 0 PID: 166 Comm: sh Not tainted 6.14.0-rc7-dirty #374
 Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015
 pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
 pc : const_folio_flags+0x3c/0x58
 lr : const_folio_flags+0x3c/0x58
 Call trace:
  const_folio_flags+0x3c/0x58 (P)
  do_migrate_range+0x164/0x720
  offline_pages+0x63c/0x6fc
  memory_subsys_offline+0x190/0x1f4
  device_offline+0xc0/0x13c
  state_store+0x90/0xd8
  dev_attr_store+0x18/0x2c
  sysfs_kf_write+0x44/0x54
  kernfs_fop_write_iter+0x120/0x1cc
  vfs_write+0x240/0x378
  ksys_write+0x70/0x108
  __arm64_sys_write+0x1c/0x28
  invoke_syscall+0x48/0x10c
  el0_svc_common.constprop.0+0x40/0xe0

When allocating a hugetlb folio, between the folio is taken from buddy and
prep_compound_page() is called, start_isolate_page_range() and
do_migrate_range() is called.  When do_migrate_range() scans the head page
of the hugetlb folio, the compound_head field isn't set, so scans the tail
page next.  And at this time, the compound_head field of tail page is set,
folio_test_large() is called by tail page, thus triggers VM_BUG_ON().

To fix it, get folio refcount before calling folio_test_large().

Link: https://lkml.kernel.org/r/20250324131750.1551884-1-tujinjiang@huawei.com
Fixes: 8135d8926c ("mm: memory_hotplug: memory hotremove supports thp migration")
Fixes: b62b51d2d1 ("mm: memory_hotplug: remove head variable in do_migrate_range()")
Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com>
Acked-by: Oscar Salvador <osalvador@suse.de>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Nanyong Sun <sunnanyong@huawei.com>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-04-01 15:17:12 -07:00
arch Driver core updates for 6.15-rc1 2025-04-01 11:02:03 -07:00
block for-6.15/block-20250322 2025-03-26 18:08:55 -07:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto This update includes the following changes: 2025-03-29 10:01:55 -07:00
Documentation Char/Misc/IIO driver updates for 6.15-rc1 2025-04-01 11:26:08 -07:00
drivers Char/Misc/IIO driver updates for 6.15-rc1 2025-04-01 11:26:08 -07:00
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init [ Merge note: this pull request depends on you having merged 2025-03-24 22:06:11 -07:00
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ipc treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
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LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm mm/memory_hotplug: fix call folio_test_large with tail page in do_migrate_range 2025-04-01 15:17:12 -07:00
net - The 6 patch series "Enable strict percpu address space checks" from 2025-04-01 09:29:18 -07:00
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sound - The 7 patch series "powerpc/crash: use generic crashkernel 2025-04-01 10:06:52 -07:00
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.clippy.toml rust: give Clippy the minimum supported Rust version 2025-01-10 00:17:25 +01:00
.cocciconfig
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.get_maintainer.ignore MAINTAINERS: Retire Ralf Baechle 2024-11-12 15:48:59 +01:00
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.gitignore rust: use host dylib naming convention to support macOS 2025-01-10 01:01:24 +01:00
.mailmap - The 7 patch series "powerpc/crash: use generic crashkernel 2025-04-01 10:06:52 -07:00
.rustfmt.toml
COPYING
CREDITS - The 6 patch series "Enable strict percpu address space checks" from 2025-04-01 09:29:18 -07:00
Kbuild drm: ensure drm headers are self-contained and pass kernel-doc 2025-02-12 10:44:43 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS MAINTAINERS: mm: add entry for secretmem 2025-04-01 15:17:12 -07:00
Makefile [ Merge note: this pull request depends on you having merged 2025-03-24 22:06:11 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

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.