The patch titled
coredump: exit_mm: clear ->mm first, then play with ->core_state
has been removed from the -mm tree. Its filename was
coredump-exit_mm-clear-mm-first-then-play-with-core_state.patch
This patch was dropped because it was withdrawn
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: coredump: exit_mm: clear ->mm first, then play with ->core_state
From: Oleg Nesterov <oleg@xxxxxxxxxx>
With the previous changes the sub-threads which participate in coredump do
not need to have the valid ->mm when the coredump is in progress, now we
can decouple exit_mm() from coredumping code.
Change exit_mm() to clear ->mm first, then play with mm->core_state. This
simplifies the code because we can avoid unlock/lock games with
->mmap_sem, and more importantly this makes the coredumping process
visible to oom_kill. Currently the PF_EXITING task can sleep with ->mm !=
NULL "unpredictably" long.
The patch moves the coredumping code to the new function for the readability.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/exec.c | 4 ++--
kernel/exit.c | 47 +++++++++++++++++++++++++----------------------
2 files changed, 27 insertions(+), 24 deletions(-)
diff -puN fs/exec.c~coredump-exit_mm-clear-mm-first-then-play-with-core_state fs/exec.c
--- a/fs/exec.c~coredump-exit_mm-clear-mm-first-then-play-with-core_state
+++ a/fs/exec.c
@@ -1637,8 +1637,8 @@ static void coredump_finish(struct mm_st
next = curr->next;
task = curr->task;
/*
- * see exit_mm(), curr->task must not see
- * ->task == NULL before we read ->next.
+ * see exit_coredump(), curr->task must not
+ * see ->task == NULL before we read ->next.
*/
smp_mb();
curr->task = NULL;
diff -puN kernel/exit.c~coredump-exit_mm-clear-mm-first-then-play-with-core_state kernel/exit.c
--- a/kernel/exit.c~coredump-exit_mm-clear-mm-first-then-play-with-core_state
+++ a/kernel/exit.c
@@ -644,6 +644,28 @@ assign_new_owner:
}
#endif /* CONFIG_MM_OWNER */
+static void exit_coredump(struct task_struct * tsk,
+ struct core_state *core_state)
+{
+ struct core_thread self;
+
+ self.task = tsk;
+ self.next = xchg(&core_state->dumper.next, &self);
+ /*
+ * Implies mb(), the result of xchg() must be visible
+ * to core_state->dumper.
+ */
+ if (atomic_dec_and_test(&core_state->nr_threads))
+ complete(&core_state->startup);
+
+ for (;;) {
+ set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+ if (!self.task) /* see coredump_finish() */
+ break;
+ schedule();
+ }
+ __set_task_state(tsk, TASK_RUNNING);
+}
/*
* Turn us into a lazy TLB process if we
* aren't already..
@@ -665,28 +687,6 @@ static void exit_mm(struct task_struct *
*/
down_read(&mm->mmap_sem);
core_state = mm->core_state;
- if (core_state) {
- struct core_thread self;
- up_read(&mm->mmap_sem);
-
- self.task = tsk;
- self.next = xchg(&core_state->dumper.next, &self);
- /*
- * Implies mb(), the result of xchg() must be visible
- * to core_state->dumper.
- */
- if (atomic_dec_and_test(&core_state->nr_threads))
- complete(&core_state->startup);
-
- for (;;) {
- set_task_state(tsk, TASK_UNINTERRUPTIBLE);
- if (!self.task) /* see coredump_finish() */
- break;
- schedule();
- }
- __set_task_state(tsk, TASK_RUNNING);
- down_read(&mm->mmap_sem);
- }
atomic_inc(&mm->mm_count);
BUG_ON(mm != tsk->active_mm);
/* more a memory barrier than a real lock */
@@ -699,6 +699,9 @@ static void exit_mm(struct task_struct *
task_unlock(tsk);
mm_update_next_owner(mm);
mmput(mm);
+
+ if (core_state)
+ exit_coredump(tsk, core_state);
}
static void
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
linux-next.patch
migrate_timers-add-comment-use-spinlock_irq.patch
pm-introduce-new-interfaces-schedule_work_on-and-queue_work_on.patch
pm-introduce-new-interfaces-schedule_work_on-and-queue_work_on-cleanup.patch
posix-timers-timer_delete-remove-the-bogus-it_process-=-null-check.patch
posix-timers-release_posix_timer-kill-the-bogus-put_task_struct-it_process.patch
signals-collect_signal-remove-the-unneeded-sigismember-check.patch
signals-collect_signal-simplify-the-still_pending-logic.patch
signals-change-collect_signal-to-return-void.patch
__exit_signal-dont-take-rcu-lock.patch
signals-dequeue_signal-dont-check-signal_group_exit-when-setting-signal_stop_dequeued.patch
signals-do_signal_stop-kill-the-signal_unkillable-check.patch
coredump-zap_threads-comments-use-while_each_thread.patch
signals-make-siginfo_t-si_utime-si_sstime-report-times-in-user_hz-not-hz.patch
kernel-signalc-change-vars-pid-and-tgid-types-to-pid_t.patch
include-asm-ptraceh-userspace-headers-cleanup.patch
ptrace-give-more-respect-to-sigkill.patch
ptrace-simplify-ptrace_stop-sigkill_pending-path.patch
introduce-pf_kthread-flag.patch
kill-pf_borrowed_mm-in-favour-of-pf_kthread.patch
coredump-zap_threads-must-skip-kernel-threads.patch
coredump-elf_core_dump-skip-kernel-threads.patch
coredump-turn-mm-core_startup_done-into-the-pointer-to-struct-core_state.patch
coredump-move-mm-core_waiters-into-struct-core_state.patch
coredump-simplify-core_state-nr_threads-calculation.patch
coredump-turn-core_state-nr_threads-into-atomic_t.patch
coredump-make-mm-core_state-visible-to-core_dump.patch
coredump-construct-the-list-of-coredumping-threads-at-startup-time.patch
coredump-elf_core_dump-use-core_state-dumper-list.patch
coredump-elf_fdpic_core_dump-use-core_state-dumper-list.patch
coredump-kill-mm-core_done.patch
coredump-exit_mm-clear-mm-first-then-play-with-core_state.patch
coredump-exit_mm-clear-mm-first-then-play-with-core_state-checkpatch-fixes.patch
workqueues-insert_work-use-list_head-instead-of-int-tail.patch
workqueues-implement-flush_work.patch
workqueues-schedule_on_each_cpu-use-flush_work.patch
workqueues-make-get_online_cpus-useable-for-work-func.patch
workqueues-make-get_online_cpus-useable-for-work-func-fix.patch
s390-topology-dont-use-kthread-for-arch_reinit_sched_domains.patch
workqueues-lockdep-annotations-for-flush_work.patch
workqueues-queue_work-can-use-queue_work_on.patch
workqueues-schedule_on_each_cpu-can-use-schedule_work_on.patch
pidns-remove-now-unused-kill_proc-function.patch
pidns-remove-now-unused-find_pid-function.patch
pidns-remove-find_task_by_pid-unused-for-a-long-time.patch
distinct-tgid-tid-i-o-statistics.patch
tracehook-add-linux-tracehookh.patch
tracehook-exec.patch
tracehook-unexport-ptrace_notify.patch
tracehook-exit.patch
tracehook-clone.patch
tracehook-vfork-done.patch
tracehook-release_task.patch
tracehook-tracehook_tracer_task.patch
tracehook-tracehook_expect_breakpoints.patch
tracehook-tracehook_signal_handler.patch
tracehook-tracehook_consider_ignored_signal.patch
tracehook-tracehook_consider_fatal_signal.patch
tracehook-syscall.patch
tracehook-get_signal_to_deliver.patch
tracehook-job-control.patch
tracehook-death.patch
tracehook-force-signal_pending.patch
tracehook-tif_notify_resume.patch
tracehook-asm-syscallh.patch
tracehook-config_have_arch_tracehook.patch
tracehook-wait_task_inactive.patch
task_current_syscall.patch
proc-pid-syscall.patch
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