On Mon, Aug 26, 2019 at 10:13:25PM +0900, Tetsuo Handa wrote: > syzbot found that a thread can stall for minutes inside read_mem() or > write_mem() after that thread was killed by SIGKILL [1]. Reading from > iomem areas of /dev/mem can be slow, depending on the hardware. > While reading 2GB at one read() is legal, delaying termination of killed > thread for minutes is bad. Thus, allow reading/writing /dev/mem and > /dev/kmem to be preemptible and killable. > > [ 1335.912419][T20577] read_mem: sz=4096 count=2134565632 > [ 1335.943194][T20577] read_mem: sz=4096 count=2134561536 > [ 1335.978280][T20577] read_mem: sz=4096 count=2134557440 > [ 1336.011147][T20577] read_mem: sz=4096 count=2134553344 > [ 1336.041897][T20577] read_mem: sz=4096 count=2134549248 > > Theoretically, reading/writing /dev/mem and /dev/kmem can become > "interruptible". But this patch chose "killable". Future patch will make > them "interruptible" so that we can revert to "killable" if some program > regressed. > > [1] > https://syzkaller.appspot.com/bug?id=a0e3436829698d5824231251fad9d8e998f94f5e > > Signed-off-by: Tetsuo Handa <[email protected]> > Reported-by: syzbot <[email protected]> > --- > drivers/char/mem.c | 21 +++++++++++++++++++++ > 1 file changed, 21 insertions(+)
What changed from previous versions? That goes below the --- line at the very least. thanks, greg k-h
