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    Subject[PATCH] exec: log when wait_for_dump_helpers aborts due to a signal
    Date
    To allow coredump pipe readers to look at /proc/<pid> of the crashing
    process, the kernel waits for the reader to exit. However, the wait
    is silently aborted if the crashing process is signalled.

    This patch, logs whenever wait_for_dump_helpers is aborted or in order
    to assist in debugging cases where /proc/<pid> is gone.

    Alternatively, we may want to consider not aborting on a signal. You
    could always break the loop by killing the reader process.

    Reference: http://crosbug.com/21559
    Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
    Cc: Alexander Viro <viro@zeniv.linux.org.uk>
    Cc: Neil Horman <nhorman@tuxdriver.com>
    Cc: Earl Chew <earl_chew@agilent.com>
    Cc: Oleg Nesterov <oleg@redhat.com>
    Cc: Andi Kleen <andi@firstfloor.org>
    Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: linux-fsdevel@vger.kernel.org
    ---
    fs/exec.c | 9 ++++++++-
    1 files changed, 8 insertions(+), 1 deletions(-)

    diff --git a/fs/exec.c b/fs/exec.c
    index 25dcbe5..5d4190d 100644
    --- a/fs/exec.c
    +++ b/fs/exec.c
    @@ -2030,7 +2030,14 @@ static void wait_for_dump_helpers(struct file *file)
    pipe->readers++;
    pipe->writers--;

    - while ((pipe->readers > 1) && (!signal_pending(current))) {
    + while (pipe->readers > 1) {
    + if (signal_pending(current)) {
    + pr_info("wait_for_dump_helpers[%d]: "
    + "aborted due to signal\n",
    + task_pid_nr(current));
    + break;
    + }
    +
    wake_up_interruptible_sync(&pipe->wait);
    kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
    pipe_wait(pipe);
    --
    1.7.3.1


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