On Fri, Nov 16, 2018 at 08:56:04AM -0800, Yang Shi wrote:
>
> > a8dda165ec vfree: add debug might_sleep()
> > dd2283f260 mm: mmap: zap pages with read mmap_sem in munmap
> > 5929a1f0ff Merge tag 'riscv-for-linus-4.20-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/palmer/riscv-linux
> > 0bc80e3cb0 Add linux-next specific files for 20181114
> > +-----------------------------------------------------+------------+------------+------------+---------------+
> > | | a8dda165ec | dd2283f260 | 5929a1f0ff | next-20181114 |
> > +-----------------------------------------------------+------------+------------+------------+---------------+
> > | boot_successes | 314 | 178 | 190 | 168 |
> > | boot_failures | 393 | 27 | 21 | 40 |
> > | WARNING:held_lock_freed | 383 | 23 | 17 | 39 |
> > | is_freeing_memory#-#,with_a_lock_still_held_there | 383 | 23 | 17 | 39 |
> > | BUG:unable_to_handle_kernel | 5 | 2 | 4 | 1 |
> > | Oops:#[##] | 9 | 3 | 4 | 1 |
> > | EIP:debug_check_no_locks_freed | 9 | 3 | 4 | 1 |
> > | Kernel_panic-not_syncing:Fatal_exception | 9 | 3 | 4 | 1 |
> > | Mem-Info | 4 | 1 | | |
> > | invoked_oom-killer:gfp_mask=0x | 1 | 1 | | |
> > | WARNING:at_kernel/locking/lockdep.c:#lock_downgrade | 0 | 6 | 4 | 7 |
> > | EIP:lock_downgrade | 0 | 6 | 4 | 7 |
> > +-----------------------------------------------------+------------+------------+------------+---------------+
> >
> > [ 96.288009] random: get_random_u32 called from arch_rnd+0x3c/0x70 with crng_init=0
> > [ 96.359626] input_id (331) used greatest stack depth: 6360 bytes left
> > [ 96.749228] grep (358) used greatest stack depth: 6336 bytes left
> > [ 96.921470] network.sh (341) used greatest stack depth: 6212 bytes left
> > [ 97.262340]
> > [ 97.262587] =========================
> > [ 97.263072] WARNING: held lock freed!
> > [ 97.263536] 4.19.0-06969-gdd2283f #1 Not tainted
> > [ 97.264110] -------------------------
> > [ 97.264575] udevd/198 is freeing memory 9c16c930-9c16c99b, with a lock still held there!
> > [ 97.265542] (ptrval) (&anon_vma->rwsem){....}, at: unlink_anon_vmas+0x14e/0x420
> > [ 97.266450] 1 lock held by udevd/198:
> > [ 97.266924] #0: (ptrval) (&mm->mmap_sem){....}, at: __do_munmap+0x531/0x730
>
> I have not figured out what this is caused by. But, the below warning looks
> more confusing. This might be caused by the below one.
I *think* we need to understand more about what detached VMAs mean for
rmap. The anon_vma for these VMAs still reachable for the rmap and
therefore VMA too. I don't quite grasp what is implications of this, but
it doesn't look good.
I'll look into this more when I get some free cycles.
It's better to disable the optimization for now (by ignoring 'downgrade'
in __do_munmap()). Before it hits release.
--
Kirill A. Shutemov
