CVE-2026-64131: mm/memory: fix spurious warning when unmapping device-private/exclusive pages

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

mm/memory: fix spurious warning when unmapping device-private/exclusive pages

Device private and exclusive entries are only supported for anonymous folios. This condition is tested in migratedevicepages() and makedeviceexclusive() using foliotestanon(). However the unmap path tests this assumption using vmaisanonymous().

This is wrong because whilst anonymous VMAs can only contain folios where foliotestanon() is true the opposite relation does not hold. A folio for which foliotestanon() is true does not imply vmaisanonymous() is true. Such a condition can occur if for example a folio is part of a private filebacked mapping.

In this case vmaisanonymous() is false as the mapping is filebacked, but foliotestanon() may be true, thus permitting devices to migrate the folio to device private memory. This can lead to the following spurious warnings during process teardown:

[ 772.737706] ------------[ cut here ]------------ [ 772.739201] WARNING: mm/memory.c:1754 at unmappagerange.cold+0x26/0x18a, CPU#17: hmm-tests/2041 [ 772.742050] Modules linked in: testhmm nvidiauvm(O) nvidia(O) [ 772.743959] CPU: 17 UID: 0 PID: 2041 Comm: hmm-tests Tainted: G W O 7.0.0+ #387 PREEMPT(full) [ 772.747104] Tainted: [W]=WARN, [O]=OOTMODULE [ 772.748509] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014 [ 772.752117] RIP: 0010:unmappagerange.cold+0x26/0x18a [ 772.753780] Code: 7e fe ff ff 48 89 4c 24 78 4c 89 44 24 38 e8 f2 ff b1 00 48 8b 4c 24 78 4c 8b 44 24 38 48 8b 44 24 18 48 83 78 48 00 74 04 90 <0f> 0b 90 48 89 ca b8 ff ff 37 00 48 c1 ea 03 48 c1 e0 2a 80 3c 02 [ 772.759602] RSP: 0018:ffff888112607550 EFLAGS: 00010286 [ 772.761310] RAX: ffff88811bbf4dc0 RBX: dffffc0000000000 RCX: ffffea03e9bfffd8 [ 772.763583] RDX: 1ffff1102377e9c1 RSI: 0000000000000008 RDI: ffff88811bbf4e08 [ 772.765914] RBP: 0000000000000006 R08: ffff8881059f7448 R09: ffffed10224c0e68 [ 772.768184] R10: ffff888112607347 R11: 0000000000000001 R12: 0000000000000001 [ 772.770461] R13: ffffea03e9bfffc0 R14: ffff888112607908 R15: ffffea03e9bfffc0 [ 772.772782] FS: 00007f327caa2780(0000) GS:ffff888427b7d000(0000) knlGS:0000000000000000 [ 772.775328] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 772.777187] CR2: 00007f327ca89000 CR3: 00000001994d5000 CR4: 00000000000006f0 [ 772.779135] Call Trace: [ 772.779792] <TASK> [ 772.780317] ? dmirrorintervalinvalidate+0x1a3/0x290 [testhmm] [ 772.781873] ? vmnormalpagepud+0x2b0/0x2b0 [ 772.782992] ? rwlockinit+0x150/0x150 [ 772.784006] ? lockrelease+0x216/0x2b0 [ 772.785008] ? mmunotifierinvalidaterangestart+0x505/0x6e0 [ 772.786522] ? lockrelease+0x216/0x2b0 [ 772.787498] ? unmapsinglevma+0xb6/0x210 [ 772.788573] unmapvmas+0x27d/0x520 [ 772.789506] ? unmapsinglevma+0x210/0x210 [ 772.790607] ? masupdategap.part.0+0x620/0x620 [ 772.791834] unmapregion+0x19e/0x350 [ 772.792769] ? removevma+0x130/0x130 [ 772.793684] ? masallocnodes+0x1f2/0x300 [ 772.794730] vmscompletemunmapvmas+0x8c1/0xe20 [ 772.795926] ? unmapregion+0x350/0x350 [ 772.796917] dovmialignmunmap+0x36a/0x4e0 [ 772.798018] ? lockrelease+0x216/0x2b0 [ 772.799024] ? vmashrink+0x620/0x620 [ 772.799983] dovmimunmap+0x150/0x2c0 [ 772.800939] vmmunmap+0x161/0x2c0 [ 772.801872] ? expanddownwards+0xd60/0xd60 [ 772.802948] ? clockeventsprogramevent+0x1ef/0x540 [ 772.804217] ? lockrelease+0x216/0x2b0 [ 772.805158] x64sysmunmap+0x59/0x80 [ 772.805776] dosyscall64+0xfc/0x670 [ 772.806336] ? irqentryexit+0xda/0x580 [ 772.806976] entrySYSCALL64afterhwframe+0x4b/0x53 [ 772.807772] RIP: 0033:0x7f327cbb2717 [ 772.808323] Code: 73 01 c3 48 8b 0d f9 76 0d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 0b 00 00 00 0f 05 <48> 3d 01 f0 ff ---truncated---