From b564daf806d492dd4f7afe9b6c83b8d35d137669 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@tv-sign.ru>
Date: Fri, 25 Jul 2008 01:47:44 -0700
Subject: [PATCH] coredump: construct the list of coredumping threads at
startup time
binfmt->core_dump() has to iterate over the all threads in system in order
to find the coredumping threads and construct the list using the
GFP_ATOMIC allocations.
With this patch each thread allocates the list node on exit_mm()'s stack and
adds itself to the list.
This allows us to do further changes:
- simplify ->core_dump()
- change exit_mm() to clear ->mm first, then wait for ->core_done.
this makes the coredumping process visible to oom_kill
- kill mm->core_done
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
fs/exec.c | 2 ++
include/linux/mm_types.h | 6 ++++++
kernel/exit.c | 15 ++++++++++++---
3 files changed, 20 insertions(+), 3 deletions(-)
diff --git a/fs/exec.c b/fs/exec.c
index b8ee842d93cdd..fe2873b8037f2 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1604,6 +1604,8 @@ static int coredump_wait(int exit_code, struct core_state *core_state)
init_completion(&mm->core_done);
init_completion(&core_state->startup);
+ core_state->dumper.task = tsk;
+ core_state->dumper.next = NULL;
core_waiters = zap_threads(tsk, mm, core_state, exit_code);
up_write(&mm->mmap_sem);
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index ae99a28ba6ae4..4d0d0abc79fe2 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -159,8 +159,14 @@ struct vm_area_struct {
#endif
};
+struct core_thread {
+ struct task_struct *task;
+ struct core_thread *next;
+};
+
struct core_state {
atomic_t nr_threads;
+ struct core_thread dumper;
struct completion startup;
};
diff --git a/kernel/exit.c b/kernel/exit.c
index 63d82957baae2..b66f0d55c7919 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -664,6 +664,7 @@ void mm_update_next_owner(struct mm_struct *mm)
static void exit_mm(struct task_struct * tsk)
{
struct mm_struct *mm = tsk->mm;
+ struct core_state *core_state;
mm_release(tsk, mm);
if (!mm)
@@ -676,11 +677,19 @@ static void exit_mm(struct task_struct * tsk)
* group with ->mm != NULL.
*/
down_read(&mm->mmap_sem);
- if (mm->core_state) {
+ core_state = mm->core_state;
+ if (core_state) {
+ struct core_thread self;
up_read(&mm->mmap_sem);
- if (atomic_dec_and_test(&mm->core_state->nr_threads))
- complete(&mm->core_state->startup);
+ 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);
wait_for_completion(&mm->core_done);
down_read(&mm->mmap_sem);
--
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