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  • [PATCH 0/1] s390: fix endless loop in do_signal

    From Sumanth Korikkar@21:1/5 to All on Wed Feb 15 13:30:01 2023
    XPost: linux.debian.ports.s390

    Hi,

    This patch fixes the issue for s390 stable kernel starting 5.10.162.
    The issue was specifically seen after stable version 5.10.162:
    Following commits can trigger it:
    1. stable commit id - 788d0824269b ("io_uring: import 5.15-stable
    io_uring") can trigger this problem.
    2. upstream commit id - 75309018a24d ("s390: add support for TIF_NOTIFY_SIGNAL")

    Problem:
    qemu and user processes could stall when TIF_NOTIFY_SIGNAL is set from
    io_uring work.

    Affected users:
    The issue was first raised by the debian team, where the s390
    bullseye build systems are affected.

    Upstream commit Id:
    * The attached patch has no upstream commit. However, the stable kernel 5.10.162+ uses upstream commit id - 75309018a24d ("s390: add support for TIF_NOTIFY_SIGNAL"), which would need this fix
    * Starting from v5.12, there are s390 generic entry commits
    56e62a737028 ("s390: convert to generic entry") and its relevant fixes,
    which are recommended and should address these problems.

    Kernel version to be applied:
    stable kernel 5.10.162+

    Thanks.
    Sumanth

    Sumanth Korikkar (1):
    s390/signal: fix endless loop in do_signal

    arch/s390/kernel/signal.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --
    2.37.2

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Greg KH@21:1/5 to Sumanth Korikkar on Wed Feb 15 15:00:02 2023
    XPost: linux.debian.ports.s390

    On Wed, Feb 15, 2023 at 01:04:12PM +0100, Sumanth Korikkar wrote:
    Hi,

    This patch fixes the issue for s390 stable kernel starting 5.10.162.
    The issue was specifically seen after stable version 5.10.162:
    Following commits can trigger it:
    1. stable commit id - 788d0824269b ("io_uring: import 5.15-stable
    io_uring") can trigger this problem.
    2. upstream commit id - 75309018a24d ("s390: add support for TIF_NOTIFY_SIGNAL")

    Problem:
    qemu and user processes could stall when TIF_NOTIFY_SIGNAL is set from io_uring work.

    Affected users:
    The issue was first raised by the debian team, where the s390
    bullseye build systems are affected.

    Upstream commit Id:
    * The attached patch has no upstream commit. However, the stable kernel 5.10.162+ uses upstream commit id - 75309018a24d ("s390: add support for TIF_NOTIFY_SIGNAL"), which would need this fix
    * Starting from v5.12, there are s390 generic entry commits
    56e62a737028 ("s390: convert to generic entry") and its relevant fixes, which are recommended and should address these problems.

    I'm sorry, but I do not understand. What exact commits should be added
    to the 5.10.y tree to resolve this?

    thanks,

    greg k-h

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Greg KH@21:1/5 to Heiko Carstens on Wed Feb 15 15:10:01 2023
    XPost: linux.debian.ports.s390

    On Wed, Feb 15, 2023 at 02:35:24PM +0100, Heiko Carstens wrote:
    On Wed, Feb 15, 2023 at 02:23:20PM +0100, Greg KH wrote:
    On Wed, Feb 15, 2023 at 01:04:12PM +0100, Sumanth Korikkar wrote:
    Hi,

    This patch fixes the issue for s390 stable kernel starting 5.10.162. The issue was specifically seen after stable version 5.10.162:
    Following commits can trigger it:
    1. stable commit id - 788d0824269b ("io_uring: import 5.15-stable io_uring") can trigger this problem.
    2. upstream commit id - 75309018a24d ("s390: add support for TIF_NOTIFY_SIGNAL")

    Problem:
    qemu and user processes could stall when TIF_NOTIFY_SIGNAL is set from io_uring work.

    Affected users:
    The issue was first raised by the debian team, where the s390
    bullseye build systems are affected.

    Upstream commit Id:
    * The attached patch has no upstream commit. However, the stable kernel 5.10.162+ uses upstream commit id - 75309018a24d ("s390: add support for TIF_NOTIFY_SIGNAL"), which would need this fix
    * Starting from v5.12, there are s390 generic entry commits
    56e62a737028 ("s390: convert to generic entry") and its relevant fixes, which are recommended and should address these problems.

    I'm sorry, but I do not understand. What exact commits should be added
    to the 5.10.y tree to resolve this?

    Only the patch sent by Sumanth as reply to this cover letter should be
    added to the 5.10.y tree.

    The problem that is addressed here is that commit 75309018a24d ("s390: add support for TIF_NOTIFY_SIGNAL") was backported to 5.10. This commit is broken, but nobody noticed upstream, since shortly after s390 converted to generic entry with commit 56e62a737028 ("s390: convert to generic entry"), which implicitly fixed that.

    Ok, then please say that in the changelog text.

    thanks,

    greg k-h

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Heiko Carstens@21:1/5 to Greg KH on Wed Feb 15 15:00:02 2023
    XPost: linux.debian.ports.s390

    On Wed, Feb 15, 2023 at 02:23:20PM +0100, Greg KH wrote:
    On Wed, Feb 15, 2023 at 01:04:12PM +0100, Sumanth Korikkar wrote:
    Hi,

    This patch fixes the issue for s390 stable kernel starting 5.10.162.
    The issue was specifically seen after stable version 5.10.162:
    Following commits can trigger it:
    1. stable commit id - 788d0824269b ("io_uring: import 5.15-stable io_uring") can trigger this problem.
    2. upstream commit id - 75309018a24d ("s390: add support for TIF_NOTIFY_SIGNAL")

    Problem:
    qemu and user processes could stall when TIF_NOTIFY_SIGNAL is set from io_uring work.

    Affected users:
    The issue was first raised by the debian team, where the s390
    bullseye build systems are affected.

    Upstream commit Id:
    * The attached patch has no upstream commit. However, the stable kernel 5.10.162+ uses upstream commit id - 75309018a24d ("s390: add support for TIF_NOTIFY_SIGNAL"), which would need this fix
    * Starting from v5.12, there are s390 generic entry commits
    56e62a737028 ("s390: convert to generic entry") and its relevant fixes, which are recommended and should address these problems.

    I'm sorry, but I do not understand. What exact commits should be added
    to the 5.10.y tree to resolve this?

    Only the patch sent by Sumanth as reply to this cover letter should be
    added to the 5.10.y tree.

    The problem that is addressed here is that commit 75309018a24d ("s390: add support for TIF_NOTIFY_SIGNAL") was backported to 5.10. This commit is
    broken, but nobody noticed upstream, since shortly after s390 converted to generic entry with commit 56e62a737028 ("s390: convert to generic entry"), which implicitly fixed that.

    I doesn't look sane to backport commit 56e62a737028 ("s390: convert to
    generic entry"), since that is huge and came with a lot of bugs, where I'm
    not sure if all bug fixes had Fixes tags.

    So the one-liner provided by Sumanth seems to be the best way to address
    this bug.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)