Re: ia64 hang/mca running gdb 'make check'

From: KAMEZAWA Hiroyuki
Date: Thu Jul 29 2010 - 20:46:49 EST

Next message: Stephen Rothwell: "linux-next: manual merge of the s5p tree with the arm tree"
Previous message: Dave Hansen: "Re: [PATCH] Tight check of pfn_valid on sparsemem - v4"
In reply to: dann frazier: "Re: ia64 hang/mca running gdb 'make check'"
Next in thread: Hugh Dickins: "Re: ia64 hang/mca running gdb 'make check'"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

On Thu, 29 Jul 2010 13:22:16 -0600
dann frazier <dannf@xxxxxxxxxx> wrote:

> On Wed, Jul 28, 2010 at 08:50:18PM -0700, Hugh Dickins wrote:
> > On Tue, 27 Jul 2010, dann frazier wrote:
> > > On Tue, Jul 27, 2010 at 06:03:30PM +0900, KAMEZAWA Hiroyuki wrote:
> > > > On Tue, 27 Jul 2010 01:19:15 -0600
> > > > dann frazier <dannf@xxxxxxxxxx> wrote:
> > > > > On Tue, Jul 20, 2010 at 09:19:50PM -0700, Hugh Dickins wrote:
> > > > > > On Tue, 20 Jul 2010, dann frazier wrote:
> > > > > > > On Wed, Jul 21, 2010 at 10:51:36AM +0900, KAMEZAWA Hiroyuki wrote:
> > > > > > > > On Tue, 20 Jul 2010 11:35:12 -0600
> > > > > > > > dann frazier <dannf@xxxxxxxxxx> wrote:
> > > > > > > >
> > > > > > > > > Debian's ia64 autobuilders have been experiencing system crashes while
> > > > > > > > > trying to run the gdb test suite:
> > > > > > > > > http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=588574
> > > > > > > > >
> > > > > > > > > I was able to reproduce this w/ the latest git tree, and bisected it
> > > > > > > > > down to this commit, introduced in 2.6.32:
> > > > > > > > >
> > > > > > > > > commit 62eede62dafb4a6633eae7ffbeb34c60dba5e7b1
> > > > > > > > > Author: Hugh Dickins <hugh.dickins@xxxxxxxxxxxxx>
> > > > > > > > > Date: Mon Sep 21 17:03:34 2009 -0700
> > > > > > > > >
> > > > > > > > > mm: ZERO_PAGE without PTE_SPECIAL
> > > > > > > > >
> > > > > > > > > Reinstate anonymous use of ZERO_PAGE to all architectures, not just to
> > > > > > > > > those which __HAVE_ARCH_PTE_SPECIAL: as suggested by Nick Piggin.
> > > > > > > > >
> > > > > > > > > Contrary to how I'd imagined it, there's nothing ugly about this, just a
> > > > > > > > > zero_pfn test built into one or another block of vm_normal_page().
> > > > > > > > >
> > > > > > > > > But the MIPS ZERO_PAGE-of-many-colours case demands is_zero_pfn() and
> > > > > > > > > my_zero_pfn() inlines. Reinstate its mremap move_pte() shuffling of
> > > > > > > > > ZERO_PAGEs we did from 2.6.17 to 2.6.19? Not unless someone shouts for
> > > > > > > > > that: it would have to take vm_flags to weed out some cases.
> > > > > > > > >
> > > > > > > > > fyi, I found this to not be reproducible on SLES11 SP1 (which is
> > > > > > > > > 2.6.32-based). I compared the .configs and found that the relevant
> > > > > > > > > difference is the PAGE_SIZE. It does not fail w/ 64KB pages, but
> > > > > > > > > reliably fails w/ 16KB pages.
> > > > > > > > >
> > > > > > > >
> > > > > > > > Sorry, I have no idea...
> > > > > > > > Hmm, what is the address of empty_zero_page[] on your debian(16kb-page) ?
> > > > > > >
> > > > > > >
> > > > > > > dannf@krebs:~$ grep empty_zero_page /boot/System.map-2.6.32-5-mckinley
> > > > > > > a0000001008784c0 d __ksymtab_empty_zero_page
> > > > > > > a000000100882688 d __kcrctab_empty_zero_page
> > > > > > > a000000100884ca4 r __kstrtab_empty_zero_page
> > > > > > > a000000100974000 D empty_zero_page
> > > > > >
> > > > > > Thanks a lot for reporting this, but I too have no idea yet.
> > > > > >
> > > > > > It is likely that the bug is not to be found in that 62eede62, but
> > > > > > rather in one of the preceding patches to mm/memory.c which 62eede62
> > > > > > was extending to ia64 and other architectures without PTE_SPECIAL.
> > > > > >
> > > > > > I wonder, from looking at that gdb testsuite log, is it plausible
> > > > > > that all these hangs/crashes occurred when writing out a coredump?
> > > > > > Is that something you could check for us? or rule out the possibility.
> > > > >
> > > > > Yep, seems so. I've reduced it down to this test case:
> > > > >
> > > > > dannf@rx2600:~> cat > foo.c
> > > > > int leaf(void) {
> > > > > return 0;
> > > > > }
> > > > >
> > > > > int main(void) {
> > > > > leaf();
> > > > > }
> > > > > dannf@rx2600:~> gcc -g foo.c -o foo
> > > > > dannf@rx2600:~> gdb ./foo
> > > > > GNU gdb (GDB) SUSE (7.0-0.4.16)
> > > > > Copyright (C) 2009 Free Software Foundation, Inc.
> > > > > License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
> > > > > This is free software: you are free to change and redistribute it.
> > > > > There is NO WARRANTY, to the extent permitted by law. Type "show copying"
> > > > > and "show warranty" for details.
> > > > > This GDB was configured as "ia64-suse-linux".
> > > > > For bug reporting instructions, please see:
> > > > > <http://www.gnu.org/software/gdb/bugs/>...
> > > > > Reading symbols from /home/dannf/foo...done.
> > > > > (gdb) break leaf
> > > > > Breakpoint 1 at 0x40000000000005c1: file foo.c, line 2.
> > > > > (gdb) run
> > > > > Starting program: /home/dannf/foo
> > > > > Missing separate debuginfo for /lib/ld-linux-ia64.so.2
> > > > > Try: zypper install -C "debuginfo(build-id)=d5bfb8b5940e174d54b978ca515dc0df76c7618c"
> > > > > Missing separate debuginfo for /lib/libc.so.6.1
> > > > > Try: zypper install -C "debuginfo(build-id)=ca78657bd9173653d95f8504a313d2b6db8cb1d6"
> > > > >
> > > > > Breakpoint 1, leaf () at foo.c:2
> > > > > 2 return 0;
> > > > > (gdb) gcore /tmp/save
> > > > >
> > > > > [bang]
> > > > >
> > > >
> > > > Does this happen on 2.6.34 or 2.6.35-rc kernel ?
> > >
> > > I've been testing w/ a 2.6.35-rc4+, though it was originally reported
> > > on a 2.6.32.
> >
> > Thanks a lot for narrowing down to that simple testcase, and
> > thanks a lot for checking it's just as bad on recent kernels.
> >
> > I'm sorry to say that I'm still just as baffled.
> >
> > Let's note that gdb's gcore is building up its own version of a
> > coredump, not going through the get_dump_page() code I was wondering
> > about. If I read gcore correctly (possibly not!), it will be reading
> > selected areas from /proc/<pid>/mem i.e. using access_process_vm().
>
> This appears to be correct. I was able to collect the following
> stacktrace using INIT:
>
> [ 2535.074197] Backtrace of pid 4605 (gdb)
> [ 2535.074197]
> [ 2535.074197] Call Trace:
> [ 2535.074197] [<a00000010000bb00>] ia64_native_leave_kernel+0x0/0x270
> [ 2535.074197] sp=e000004081c77c40 bsp=e000004081c71018
> [ 2535.074197] [<a000000100334720>] __copy_user+0x160/0x960
> [ 2535.074197] sp=e000004081c77e10 bsp=e000004081c71018
> [ 2535.074197] [<a000000100176b00>] access_process_vm+0x2c0/0x380
> [ 2535.074197] sp=e000004081c77e10 bsp=e000004081c70f60
>

Could you show full stack ? IIUC, ia64's gdb has to call both of strace(PEEK) and
/proc/pid/mem to check hidden regiter stack.

Thanks,
-Kame

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Next message: Stephen Rothwell: "linux-next: manual merge of the s5p tree with the arm tree"
Previous message: Dave Hansen: "Re: [PATCH] Tight check of pfn_valid on sparsemem - v4"
In reply to: dann frazier: "Re: ia64 hang/mca running gdb 'make check'"
Next in thread: Hugh Dickins: "Re: ia64 hang/mca running gdb 'make check'"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]