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From:   Yu Zhao <yuzhao@google.com>
Date:   Wed, 15 Jun 2022 19:58:34 -0600
Message-ID: <CAOUHufZtq0PDiGXBvLV=POraK-4dfnQ9UNmsafHhJmzxAhzrfw@mail.gmail.com>
Subject: Re: [PATCH v9 28/69] mm/mmap: reorganize munmap to use maple states
To:     Liam Howlett <liam.howlett@oracle.com>
Cc:     Qian Cai <quic_qiancai@quicinc.com>,
        "maple-tree@lists.infradead.org" <maple-tree@lists.infradead.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
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On Wed, Jun 15, 2022 at 7:50 PM Liam Howlett <liam.howlett@oracle.com> wrote:
>
> * Yu Zhao <yuzhao@google.com> [220615 17:17]:
>
> ...
>
> > > Yes, I used the same parameters with 512GB of RAM, and the kernel with
> > > KASAN and other debug options.
> >
> > Sorry, Liam. I got the same crash :(
>
> Thanks for running this promptly.  I am trying to get my own server
> setup now.
>
> >
> > 9d27f2f1487a (tag: mm-everything-2022-06-14-19-05, akpm/mm-everything)
> > 00d4d7b519d6 fs/userfaultfd: Fix vma iteration in mas_for_each() loop
> > 55140693394d maple_tree: Make mas_prealloc() error checking more generic
> > 2d7e7c2fcf16 maple_tree: Fix mt_destroy_walk() on full non-leaf non-alloc nodes
> > 4d4472148ccd maple_tree: Change spanning store to work on larger trees
> > ea36bcc14c00 test_maple_tree: Add tests for preallocations and large
> > spanning writes
> > 0d2aa86ead4f mm/mlock: Drop dead code in count_mm_mlocked_page_nr()
> >
> > ==================================================================
> > BUG: KASAN: slab-out-of-bounds in mab_mas_cp+0x2d9/0x6c0
> > Write of size 136 at addr ffff88c35a3b9e80 by task stress-ng/19303
> >
> > CPU: 66 PID: 19303 Comm: stress-ng Tainted: G S        I       5.19.0-smp-DEV #1
> > Call Trace:
> >  <TASK>
> >  dump_stack_lvl+0xc5/0xf4
> >  print_address_description+0x7f/0x460
> >  print_report+0x10b/0x240
> >  ? mab_mas_cp+0x2d9/0x6c0
> >  kasan_report+0xe6/0x110
> >  ? mast_spanning_rebalance+0x2634/0x29b0
> >  ? mab_mas_cp+0x2d9/0x6c0
> >  kasan_check_range+0x2ef/0x310
> >  ? mab_mas_cp+0x2d9/0x6c0
> >  ? mab_mas_cp+0x2d9/0x6c0
> >  memcpy+0x44/0x70
> >  mab_mas_cp+0x2d9/0x6c0
> >  mas_spanning_rebalance+0x1a3e/0x4f90
>
> Does this translate to an inline around line 2997?
> And then probably around 2808?

$ ./scripts/faddr2line vmlinux mab_mas_cp+0x2d9
mab_mas_cp+0x2d9/0x6c0:
mab_mas_cp at lib/maple_tree.c:1988
$ ./scripts/faddr2line vmlinux mas_spanning_rebalance+0x1a3e
mas_spanning_rebalance+0x1a3e/0x4f90:
mast_cp_to_nodes at lib/maple_tree.c:?
(inlined by) mas_spanning_rebalance at lib/maple_tree.c:2997
$ ./scripts/faddr2line vmlinux mas_wr_spanning_store+0x16c5
mas_wr_spanning_store+0x16c5/0x1b80:
mas_wr_spanning_store at lib/maple_tree.c:?

No idea why faddr2line didn't work for the last two addresses. GDB
seems more reliable.

(gdb) li *(mab_mas_cp+0x2d9)
0xffffffff8226b049 is in mab_mas_cp (lib/maple_tree.c:1988).
(gdb) li *(mas_spanning_rebalance+0x1a3e)
0xffffffff822633ce is in mas_spanning_rebalance (lib/maple_tree.c:2801).
quit)
(gdb) li *(mas_wr_spanning_store+0x16c5)
0xffffffff8225cfb5 is in mas_wr_spanning_store (lib/maple_tree.c:4030).