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 lASaWwVe OJ3OsaiyGBMAjAhXzuQM5mIkhG9Bi2ByegLPeoBOgiXppVl2y4oy9Ltr/rC7T7nJlR8GVS13i6kyN2JSDVxpqfMKKUSqnk7TxYYH6j4jIJ0LOO+SlSm+slk5T1CJyODuUkMYd/EZvkiU0iKN/tcED3nsLJq/8Mqhiampa+DuHNwgd5nysYtknpRYVR9OUkfELZt+WHXm34qFxGZ2X+njdSGuCvUHD3w/FHgsVX735yEZ4wQ0ZFa+G4+iuEgbLJp5Eh+CnfIvoiMhXS2FVCG96p3+vnVlqkp5gQHav3oMvvM/+QUg8ipMc/k//QZP8A/cM14NZkFuWZITtjndbP1KpbgVvU+7Rk1ZsLcrbWKRVt4tI3EtO5xFTR1LpqSRYuadJxEwbnYjiTSO/P2Sd6y50LYdvLyXggXdZMRy6pA749KVoAFObuJTRWcYv/HoDqHJgwb7dYRE9lymJijcA7HrWx6EQiTLinoXUDJWH Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 5/15/26 14:05, Mika Penttilä wrote: > Hi, > >> FYI: While testing with hmm_tests I ran into >> >> [ 107.866004] ============================================ >> [ 107.866284] WARNING: possible recursive locking detected >> [ 107.866577] 7.1.0-rc3-00311-g4277273ca0e1 #12 Not tainted >> [ 107.866877] -------------------------------------------- >> [ 107.867217] hmm-tests/1098 is trying to acquire lock: >> [ 107.867491] ffff888113571b38 (&mm->mmap_lock){++++}-{4:4}, at: dmirror_range_fault+0x147/0x610 [test_hmm] <- line 368 of lib/test_hmm.c >> [ 107.868076] >> [ 107.868076] but task is already holding lock: >> [ 107.868383] ffff888113571b38 (&mm->mmap_lock){++++}-{4:4}, at: dmirror_fault_and_migrate_to_device.constprop.0+0x3aa/0x6a0 [test_hmm] <- line 1267 of lib/test_hmm.c >> [ 107.869076] >> [ 107.869076] other info that might help us debug this: >> [ 107.869415] Possible unsafe locking scenario: >> [ 107.869415] >> [ 107.869729] CPU0 >> [ 107.869866] ---- >> [ 107.870054] lock(&mm->mmap_lock); >> [ 107.870247] lock(&mm->mmap_lock); >> [ 107.870436] >> [ 107.870436] *** DEADLOCK *** >> [ 107.870436] >> [ 107.870743] May be due to missing lock nesting notation >> [ 107.870743] >> [ 107.871158] 1 lock held by hmm-tests/1098: >> [ 107.871377] #0: ffff888113571b38 (&mm->mmap_lock){++++}-{4:4}, at: dmirror_fault_and_migrate_to_device.constprop.0+0x3aa/0x6a0 [test_hmm] >> [ 107.872081] >> [ 107.872081] stack backtrace: >> [ 107.872348] CPU: 1 UID: 0 PID: 1098 Comm: hmm-tests Not tainted 7.1.0-rc3-00311-g4277273ca0e1 #12 PREEMPT(full) >> [ 107.872350] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS edk2-20260213-6.fc44 02/13/2026 >> [ 107.872354] Call Trace: >> [ 107.872357] >> [ 107.872358] dump_stack_lvl+0x5d/0x80 >> [ 107.872385] print_deadlock_bug.cold+0xc0/0xe2 >> [ 107.872393] __lock_acquire+0x10cf/0x1b90 >> [ 107.872400] lock_acquire+0x189/0x2f0 >> [ 107.872401] ? dmirror_range_fault+0x147/0x610 [test_hmm] >> [ 107.872404] down_read+0x9b/0x4b0 >> [ 107.872420] ? dmirror_range_fault+0x147/0x610 [test_hmm] >> [ 107.872421] ? lock_acquire+0x189/0x2f0 >> [ 107.872422] ? __pfx_down_read+0x10/0x10 >> [ 107.872424] ? __lock_acquire+0x3c2/0x1b90 >> [ 107.872425] dmirror_range_fault+0x147/0x610 [test_hmm] >> [ 107.872427] ? __pfx_down_read+0x10/0x10 >> [ 107.872429] ? __pfx_dmirror_range_fault+0x10/0x10 [test_hmm] >> [ 107.872430] ? __lock_acquire+0x3c2/0x1b90 >> [ 107.872434] dmirror_fault_and_migrate_to_device.constprop.0+0x3bf/0x6a0 [test_hmm] >> [ 107.872436] ? __pfx_dmirror_fault_and_migrate_to_device.constprop.0+0x10/0x10 [test_hmm] >> [ 107.872439] ? find_held_lock+0x2b/0x80 >> [ 107.872444] ? dmirror_device_remove_chunks+0x5b8/0xa00 [test_hmm] >> [ 107.872445] ? __is_insn_slot_addr+0xee/0x1f0 >> [ 107.872458] ? lock_acquire+0x189/0x2f0 >> [ 107.872460] ? avc_has_extended_perms+0x234/0x1350 >> [ 107.872476] ? __might_fault+0x89/0x150 >> [ 107.872484] ? lock_release+0xe1/0x320 >> [ 107.872486] dmirror_fops_unlocked_ioctl+0x9ba/0xdb0 [test_hmm] >> [ 107.872488] ? ioctl_has_perm.constprop.0.isra.0+0x2fe/0x6c0 >> [ 107.872494] ? __pfx_dmirror_fops_unlocked_ioctl+0x10/0x10 [test_hmm] >> [ 107.872498] ? count_memcg_events_mm.constprop.0+0x22/0x1a0 >> [ 107.872499] ? __pfx_ioctl_has_perm.constprop.0.isra.0+0x10/0x10 >> [ 107.872501] ? count_memcg_events_mm.constprop.0+0xaa/0x1a0 >> [ 107.872503] ? lock_release+0xe1/0x320 >> [ 107.872504] ? find_held_lock+0x2b/0x80 >> [ 107.872506] ? exc_page_fault+0x7e/0xf0 >> [ 107.872510] __x64_sys_ioctl+0x13c/0x1d0 >> [ 107.872521] ? lockdep_hardirqs_on_prepare+0xd9/0x190 >> [ 107.872523] do_syscall_64+0xf3/0x6a0 >> [ 107.872526] ? exc_page_fault+0xde/0xf0 >> [ 107.872528] entry_SYSCALL_64_after_hwframe+0x77/0x7f >> [ 107.872529] RIP: 0033:0x7f7381c543ad >> [ 107.872531] Code: 04 25 28 00 00 00 48 89 45 c8 31 c0 48 8d 45 10 c7 45 b0 10 00 00 00 48 89 45 b8 48 8d 45 d0 48 89 45 c0 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1a 48 8b 45 c8 64 48 2b 04 25 28 00 00 00 >> [ 107.872532] RSP: 002b:00007ffc3160a9b0 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 >> [ 107.872539] RAX: ffffffffffffffda RBX: 00007f7381b44000 RCX: 00007f7381c543ad >> [ 107.872540] RDX: 00007ffc3160aa30 RSI: 00000000c0284803 RDI: 0000000000000022 >> [ 107.872541] RBP: 00007ffc3160aa00 R08: 00000000ffffffff R09: 0000000000000000 >> [ 107.872541] R10: 0000000000000022 R11: 0000000000000246 R12: 00007ffc3160aa24 >> [ 107.872542] R13: 000000000041f380 R14: 0000000000000200 R15: 00007f7381200000 >> [ 107.872544] >> >> >> Thanks, >> Balbir >> > Thanks, I could reproduce. Had lockdep dropped off so went unnoticed. It is nesting mmap_read_lock in the test suite, I will change that in next version. > > --Mika > > I'll wait for the next version Balbir