Re: frequent lockups in 3.18rc4
From: Will Deacon
Date: Thu Dec 04 2014 - 05:51:05 EST
On Mon, Dec 01, 2014 at 06:36:04PM +0000, Linus Torvalds wrote:
> On Mon, Dec 1, 2014 at 10:25 AM, Kirill A. Shutemov
> <kirill@xxxxxxxxxxxxx> wrote:
> > No idea about oom_score, but kernel happily accepts chmod on any file
> > under /proc/PID/net/.
> /proc used to accept that fairly widely, but no, we tightened things
> down, and core /proc files end up not accepting chmod. See
> if (attr->ia_valid & ATTR_MODE)
> return -EPERM;
> although particular /proc files could choose to not use 'proc_setattr'
> if they want to.
> The '/proc/pid/net' subtree is obviously not doing that. No idea why,
> and probably for no good reason.
I just hit another one of these, but it's slightly different this time:
[child1:811]  execve(name="/proc/610/attr/keycreate", argv=0x3a044bf0, envp=0x3a04c810)
this guy disappears off into the execve and never returns. A little later,
another guy gets stuck on a completion after a sync:
[child0:856]  sync()
trinity-c0 D ffffffc000087570 0 856 612 0x00000000
The backtrace for 811 looks bogus to me (or we're missing some entries):
trinity-c1 R running task 0 811 612 0x00000000
and, as before, it has a weird child process that I can't backtrace:
trinity-c1 R running task 0 861 811 0x00000000
The RCU stall detector gets cross too, but the stall ends before it has
a chance to dump anything.
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