Messages in this thread Patch in this message | | | From | Mandeep Singh Baines <> | Subject | [PATCH 5/5] coredump: ignore non-fatal signals when core dumping to a pipe | Date | Sat, 16 Feb 2013 01:53:26 -0800 |
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From: Ben Chan <benchan@chromium.org>
Make wait_for_dump_helpers() not abort piping the core dump data when the crashing process has received a non-fatal signal. The abort still occurs in the case of SIGKILL.
Testing:
localhost ~ # echo "|/usr/bin/sleep 1d" > /proc/sys/kernel/core_pattern localhost ~ # sleep 1d & [1] 2514 localhost ~ # kill -ABRT $! # Cause coredump localhost ~ # kill -USR1 $! # Send non-fatal signal localhost ~ # top -p $! -n1 -b # Verify that we aren't dead or busy waiting top - 16:45:34 up 2 min, 0 users, load average: 0.71, 0.42, 0.17 Tasks: 1 total, 0 running, 1 sleeping, 0 stopped, 0 zombie Cpu(s): 26.0%us, 8.5%sy, 0.0%ni, 65.1%id, 0.2%wa, 0.0%hi, 0.1%si, 0.0%st Mem: 991516k total, 418556k used, 572960k free, 5948k buffers Swap: 0k total, 0k used, 0k free, 289928k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 2514 root 20 0 1868 392 336 S 0 0.0 0:00.00 sleep
localhost ~ # echo mem > /sys/power/state # Suspend localhost ~ # top -p $! -n1 -b # Verify that we aren't dead or busy waiting top - 16:46:46 up 3 min, 0 users, load average: 1.68, 0.69, 0.28 Tasks: 1 total, 0 running, 1 sleeping, 0 stopped, 0 zombie Cpu(s): 24.1%us, 7.7%sy, 0.0%ni, 67.9%id, 0.2%wa, 0.0%hi, 0.1%si, 0.0%st Mem: 991516k total, 419956k used, 571560k free, 5996k buffers Swap: 0k total, 0k used, 0k free, 290208k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 2514 root 20 0 1868 392 336 S 0 0.0 0:00.00 sleep
localhost ~ # kill -KILL $! [1]+ Aborted (core dumped) sleep 1d
Addresses http://crosbug.com/21559
Changes since v1: * Mandeep Singh Baines * To prevent blocking suspend, add try_to_freeze(). Changes since v2: * LKML: <20130215150117.GB30829@redhat.com> Oleg Nestorov * Block non-fatal signals to avoid poll_wait busy waiting. * LKML: <20130215152538.9a61a44e.akpm@linux-foundation.org> Andrew Morton * Added comment re: try_to_freeze and clarified commit message. Changes since v3: * Mandeep Singh Baines * Clear signal pending caused by fake signal from freeze_task(). * Document how the patch was tested. Changes since v4: * Mandeep Singh Baines * Moved clearing of fake signal to __refrigerator() (separate patch). * SIGKILL will remain in shared_pending since SIGNAL_GROUP_EXIT is set, so fatal_signal_pending() will return false. Add a sigkill_pending() helper that does the right thing.
Signed-off-by: Ben Chan <benchan@chromium.org> Signed-off-by: Mandeep Singh Baines <msb@chromium.org> CC: Oleg Nesterov <oleg@redhat.com> CC: Tejun Heo <tj@kernel.org> CC: Andrew Morton <akpm@linux-foundation.org> CC: Rafael J. Wysocki <rjw@sisk.pl> CC: Ingo Molnar <mingo@redhat.com> --- fs/coredump.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-)
diff --git a/fs/coredump.c b/fs/coredump.c index 1774932..3eb799d 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -32,6 +32,7 @@ #include <linux/pipe_fs_i.h> #include <linux/oom.h> #include <linux/compat.h> +#include <linux/freezer.h> #include <asm/uaccess.h> #include <asm/mmu_context.h> @@ -407,9 +408,21 @@ static void coredump_finish(struct mm_struct *mm) mm->core_state = NULL; } +static int sigkill_pending(struct task_struct *tsk) +{ + return signal_pending(tsk) && + (sigismember(&tsk->pending.signal, SIGKILL) || + sigismember(&tsk->signal->shared_pending.signal, SIGKILL)); +} + static void wait_for_dump_helpers(struct file *file) { struct pipe_inode_info *pipe; + sigset_t blocked, previous; + + /* Block all but fatal signals. */ + siginitsetinv(&blocked, sigmask(SIGKILL)); + sigprocmask(SIG_BLOCK, &blocked, &previous); pipe = file->f_path.dentry->d_inode->i_pipe; @@ -417,16 +430,26 @@ static void wait_for_dump_helpers(struct file *file) pipe->readers++; pipe->writers--; - while ((pipe->readers > 1) && (!signal_pending(current))) { + while ((pipe->readers > 1) && (!sigkill_pending(current))) { wake_up_interruptible_sync(&pipe->wait); kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); pipe_wait(pipe); + + /* + * Non-fatal signals are blocked. So we need to try + * to freeze in order to not block suspend. + */ + pipe_unlock(pipe); + try_to_freeze(); + pipe_lock(pipe); } pipe->readers--; pipe->writers++; pipe_unlock(pipe); + /* Restore signals. */ + sigprocmask(SIG_SETMASK, &previous, NULL); } /* -- 1.7.12.4
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