On Sun, Jan 29, 2017 at 6:22 PM, Vlastimil Babka <[email protected]> wrote: > On 29.1.2017 13:44, Dmitry Vyukov wrote: >> Hello, >> >> I've got the following deadlock report while running syzkaller fuzzer >> on f37208bc3c9c2f811460ef264909dfbc7f605a60: >> >> [ INFO: possible circular locking dependency detected ] >> 4.10.0-rc5-next-20170125 #1 Not tainted >> ------------------------------------------------------- >> syz-executor3/14255 is trying to acquire lock: >> (cpu_hotplug.dep_map){++++++}, at: [<ffffffff814271c7>] >> get_online_cpus+0x37/0x90 kernel/cpu.c:239 >> >> but task is already holding lock: >> (pcpu_alloc_mutex){+.+.+.}, at: [<ffffffff81937fee>] >> pcpu_alloc+0xbfe/0x1290 mm/percpu.c:897 >> >> which lock already depends on the new lock. > > I suspect the dependency comes from recent changes in drain_all_pages(). They > were later redone (for other reasons, but nice to have another validation) in > the mmots patch [1], which AFAICS is not yet in mmotm and thus linux-next. > Could > you try if it helps?
It happened only once on linux-next, so I can't verify the fix. But I will watch out for other occurrences.
