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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>
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.