CVE-2025-21931

In the Linux kernel, the following vulnerability has been resolved:

hwpoison, memory_hotplug: lock folio before unmap hwpoisoned folio

Commit b15c87263a69 ("hwpoison, memoryhotplug: allow hwpoisoned pages to be offlined) add page poison checks in domigraterange in order to make offline hwpoisoned page possible by introducing isolatelrupage and trytounmap for hwpoisoned page. However folio lock must be held before calling tryto_unmap. Add it to fix this problem.

Warning will be produced if folio is not locked during unmap:

------------[ cut here ]------------ kernel BUG at ./include/linux/swapops.h:400! Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP Modules linked in: CPU: 4 UID: 0 PID: 411 Comm: bash Tainted: G W 6.13.0-rc1-00016-g3c434c7ee82a-dirty #41 Tainted: [W]=WARN Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015 pstate: 40400005 (nZcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : trytounmapone+0xb08/0xd3c lr : trytounmapone+0x3dc/0xd3c Call trace: trytounmapone+0xb08/0xd3c (P) trytounmapone+0x3dc/0xd3c (L) rmapwalkanon+0xdc/0x1f8 rmapwalk+0x3c/0x58 trytounmap+0x88/0x90 unmappoisonedfolio+0x30/0xa8 domigraterange+0x4a0/0x568 offlinepages+0x5a4/0x670 memoryblockaction+0x17c/0x374 memorysubsysoffline+0x3c/0x78 deviceoffline+0xa4/0xd0 statestore+0x8c/0xf0 devattrstore+0x18/0x2c sysfskfwrite+0x44/0x54 kernfsfopwriteiter+0x118/0x1a8 vfswrite+0x3a8/0x4bc ksyswrite+0x6c/0xf8 _arm64syswrite+0x1c/0x28 invokesyscall+0x44/0x100 el0svccommon.constprop.0+0x40/0xe0 doel0svc+0x1c/0x28 el0svc+0x30/0xd0 el0t64synchandler+0xc8/0xcc el0t64_sync+0x198/0x19c Code: f9407be0 b5fff320 d4210000 17ffff97 (d4210000) ---[ end trace 0000000000000000 ]---