Re: WARNING in __put_task_struct (2)

[Leon Romanovsky]

On Mon, Oct 08, 2018 at 01:45:13PM -0600, Jason Gunthorpe wrote:
> On Mon, Oct 08, 2018 at 06:15:22PM +0200, Dmitry Vyukov wrote:
> > On Mon, Oct 8, 2018 at 6:12 PM, syzbot
> > <syzbot+1ed9dfaa984c88cf0ef8@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> > > Hello,
> > >
> > > syzbot found the following crash on:
> > >
> > > HEAD commit:    ae16eea39a86 Add linux-next specific files for 20181008
> > > git tree:       linux-next
> > > console output: https://syzkaller.appspot.com/x/log.txt?x=12e7c6a1400000
> > > kernel config:  https://syzkaller.appspot.com/x/.config?x=42525ce985d1a955
> > > dashboard link: https://syzkaller.appspot.com/bug?extid=1ed9dfaa984c88cf0ef8
> > > compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> > >
> > > Unfortunately, I don't have any reproducer for this crash yet.
> > >
> > > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > > Reported-by: syzbot+1ed9dfaa984c88cf0ef8@xxxxxxxxxxxxxxxxxxxxxxxxx
> >
> >
> > This was triggered by the following program, all is rdma-related, so
> > +rdma maintainers.
> >
> > 10:27:26 executing program 5:
> > r0 = openat$rdma_cm(0xffffffffffffff9c,
> > &(0x7f0000000380)='/dev/infiniband/rdma_cm\x00', 0x2, 0x0)
> > write$RDMA_USER_CM_CMD_CREATE_ID(r0, &(0x7f0000000080)={0x0, 0x18,
> > 0xfa00, {0x0, &(0x7f0000000040)={<r1=>0xffffffffffffffff}, 0x13f}},
> > 0x12d)
> > write$RDMA_USER_CM_CMD_RESOLVE_IP(r0, &(0x7f0000000200)={0x3, 0x40,
> > 0xfa00, {{0xa, 0x4e21}, {0xa, 0x0, 0x0, @mcast1}, r1}}, 0x48)
> > write$RDMA_USER_CM_CMD_CREATE_ID(r0, &(0x7f0000000340)={0x0, 0x18,
> > 0xfa00, {0x0, &(0x7f0000000300)={<r2=>0xffffffffffffffff}, 0x13f}},
> > 0x20)
> > write$RDMA_USER_CM_CMD_SET_OPTION(r0, &(0x7f00000002c0)={0xe, 0x18,
> > 0xfa00, @id_afonly={&(0x7f0000000000)=0x1, r1, 0x0, 0x2, 0x4}}, 0x20)
> > write$RDMA_USER_CM_CMD_RESOLVE_IP(r0, &(0x7f0000000100)={0x3, 0x40,
> > 0xfa00, {{0x2, 0x4e21}, {0xa, 0x0, 0x0, @local}, r2}}, 0x1ff)
> > write$RDMA_USER_CM_CMD_DESTROY_ID(r0, &(0x7f0000000180)={0x1, 0x10,
> > 0xfa00, {&(0x7f00000000c0), r2}}, 0x18)
>
> This might be fixed in Linux-next now by this commit:
>
> Author: Leon Romanovsky <leonro@xxxxxxxxxxxx>
> Date:   Tue Oct 2 11:48:03 2018 +0300
>
>     RDMA/restrack: Release task struct which was hold by CM_ID object

Jason,

I afraid that the opposite it more accurate.

This issue was introduced by that commit and According to linux-next
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next-history.git/tag/?h=next-20181008
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next-history.git/commit/?h=next-20181008&id=ae16eea39a86735f4ed0b5a6e9fe43c6cedb13b3
The RDMA tree has commit ed7a01fd3fd77f40b4ef2562b966a5decd8928d2,
which is exactly the one you cited above.
https://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git/commit/?h=for-next&id=ed7a01fd3fd77f40b4ef2562b966a5decd8928d2

Any ideas how?

Thanks

>
>
> Jason

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