On Mon 2018-11-12 12:54:45, Chanho Min wrote: > Suspend fails due to the exec family of functions blocking the freezer. > The casue is that de_thread() sleeps in TASK_UNINTERRUPTIBLE waiting for > all sub-threads to die, and we have the deadlock if one of them is frozen. > This also can occur with the schedule() waiting for the group thread leader > to exit if it is frozen. > > In our machine, it causes freeze timeout as bellows. > > Freezing of tasks failed after 20.010 seconds (1 tasks refusing to freeze, wq_busy=0): > setcpushares-ls D ffffffc00008ed70 0 5817 1483 0x0040000d > Call trace: > [<ffffffc00008ed70>] __switch_to+0x88/0xa0 > [<ffffffc000d1c30c>] __schedule+0x1bc/0x720 > [<ffffffc000d1ca90>] schedule+0x40/0xa8 > [<ffffffc0001cd784>] flush_old_exec+0xdc/0x640 > [<ffffffc000220360>] load_elf_binary+0x2a8/0x1090 > [<ffffffc0001ccff4>] search_binary_handler+0x9c/0x240 > [<ffffffc00021c584>] load_script+0x20c/0x228 > [<ffffffc0001ccff4>] search_binary_handler+0x9c/0x240 > [<ffffffc0001ce8e0>] do_execveat_common.isra.14+0x4f8/0x6e8 > [<ffffffc0001cedd0>] compat_SyS_execve+0x38/0x48 > [<ffffffc00008de30>] el0_svc_naked+0x24/0x28 > > To fix this, make de_thread() freezable. It looks safe and works fine. > > Changes in v2: > - changes for the same reason in "if (!thread_group_leader(tsk))" branch. > (reported by Oleg) > > Suggested-by: Oleg Nesterov <oleg@xxxxxxxxxx> > Signed-off-by: Chanho Min <chanho.min@xxxxxxx> Acked-by: Pavel Machek <pavel@xxxxxx> -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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