Now that we have core_state->dumper list we can use it to wake up the
sub-threads waiting for the coredump completion.
This uglifies the code and .text grows by 47 bytes, but otoh mm_struct
lessens by sizeof(struct completion). Also, with this change we can
decouple exit_mm() from the coredumping code.
Signed-off-by: Oleg Nesterov <[email protected]>
include/linux/mm_types.h | 4 +---
kernel/exit.c | 8 +++++++-
fs/exec.c | 25 ++++++++++++++++++++++---
3 files changed, 30 insertions(+), 7 deletions(-)
--- 26-rc2/include/linux/mm_types.h~5_KILL_CORE_DONE 2008-07-13 18:28:36.000000000 +0400
+++ 26-rc2/include/linux/mm_types.h 2008-07-15 17:06:58.000000000 +0400
@@ -229,9 +229,7 @@ struct mm_struct {
unsigned long flags; /* Must use atomic bitops to access the bits */
- /* coredumping support */
- struct core_state *core_state;
- struct completion core_done;
+ struct core_state *core_state; /* coredumping support */
/* aio bits */
rwlock_t ioctx_list_lock; /* aio lock */
--- 26-rc2/kernel/exit.c~5_KILL_CORE_DONE 2008-07-13 19:58:19.000000000 +0400
+++ 26-rc2/kernel/exit.c 2008-07-15 17:06:58.000000000 +0400
@@ -680,7 +680,13 @@ static void exit_mm(struct task_struct *
if (atomic_dec_and_test(&core_state->nr_threads))
complete(&core_state->startup);
- wait_for_completion(&mm->core_done);
+ for (;;) {
+ set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+ if (!self.task) /* see coredump_finish() */
+ break;
+ schedule();
+ }
+ __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
down_read(&mm->mmap_sem);
}
atomic_inc(&mm->mm_count);
--- 26-rc2/fs/exec.c~5_KILL_CORE_DONE 2008-07-13 18:43:39.000000000 +0400
+++ 26-rc2/fs/exec.c 2008-07-15 17:54:45.000000000 +0400
@@ -1597,7 +1597,6 @@ static int coredump_wait(int exit_code,
struct completion *vfork_done;
int core_waiters;
- init_completion(&mm->core_done);
init_completion(&core_state->startup);
core_state->dumper.task = tsk;
core_state->dumper.next = NULL;
@@ -1623,6 +1622,27 @@ fail:
return core_waiters;
}
+static void coredump_finish(struct mm_struct *mm)
+{
+ struct core_thread *curr, *next;
+ struct task_struct *task;
+
+ next = mm->core_state->dumper.next;
+ while ((curr = next) != NULL) {
+ next = curr->next;
+ task = curr->task;
+ /*
+ * see exit_mm(), curr->task must not see
+ * ->task == NULL before we read ->next.
+ */
+ smp_mb();
+ curr->task = NULL;
+ wake_up_process(task);
+ }
+
+ mm->core_state = NULL;
+}
+
/*
* set_dumpable converts traditional three-value dumpable to two flags and
* stores them into mm->flags. It modifies lower two bits of mm->flags, but
@@ -1807,8 +1827,7 @@ fail_unlock:
argv_free(helper_argv);
current->fsuid = fsuid;
- complete_all(&mm->core_done);
- mm->core_state = NULL;
+ coredump_finish(mm);
fail:
return retval;
}
On 07/15, Oleg Nesterov wrote:
>
> + for (;;) {
> + set_task_state(tsk, TASK_UNINTERRUPTIBLE);
> + if (!self.task) /* see coredump_finish() */
> + break;
> + schedule();
> + }
> + __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
^^^^^^^^^^^^^^^^^^^^
Ugh, sorry, this should be TASK_RUNNING. Please find the fixed patch below.
[PATCH] coredump: kill mm->core_done
Now that we have core_state->dumper list we can use it to wake up the
sub-threads waiting for the coredump completion.
This uglifies the code and .text grows by 47 bytes, but otoh mm_struct
lessens by sizeof(struct completion). Also, with this change we can
decouple exit_mm() from the coredumping code.
Signed-off-by: Oleg Nesterov <[email protected]>
include/linux/mm_types.h | 4 +---
kernel/exit.c | 8 +++++++-
fs/exec.c | 25 ++++++++++++++++++++++---
3 files changed, 30 insertions(+), 7 deletions(-)
--- 26-rc2/include/linux/mm_types.h~5_KILL_CORE_DONE 2008-07-13 18:28:36.000000000 +0400
+++ 26-rc2/include/linux/mm_types.h 2008-07-15 17:06:58.000000000 +0400
@@ -229,9 +229,7 @@ struct mm_struct {
unsigned long flags; /* Must use atomic bitops to access the bits */
- /* coredumping support */
- struct core_state *core_state;
- struct completion core_done;
+ struct core_state *core_state; /* coredumping support */
/* aio bits */
rwlock_t ioctx_list_lock; /* aio lock */
--- 26-rc2/kernel/exit.c~5_KILL_CORE_DONE 2008-07-13 19:58:19.000000000 +0400
+++ 26-rc2/kernel/exit.c 2008-07-15 20:17:28.000000000 +0400
@@ -680,7 +680,13 @@ static void exit_mm(struct task_struct *
if (atomic_dec_and_test(&core_state->nr_threads))
complete(&core_state->startup);
- wait_for_completion(&mm->core_done);
+ 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);
--- 26-rc2/fs/exec.c~5_KILL_CORE_DONE 2008-07-13 18:43:39.000000000 +0400
+++ 26-rc2/fs/exec.c 2008-07-15 20:16:36.000000000 +0400
@@ -1597,7 +1597,6 @@ static int coredump_wait(int exit_code,
struct completion *vfork_done;
int core_waiters;
- init_completion(&mm->core_done);
init_completion(&core_state->startup);
core_state->dumper.task = tsk;
core_state->dumper.next = NULL;
@@ -1623,6 +1622,27 @@ fail:
return core_waiters;
}
+static void coredump_finish(struct mm_struct *mm)
+{
+ struct core_thread *curr, *next;
+ struct task_struct *task;
+
+ next = mm->core_state->dumper.next;
+ while ((curr = next) != NULL) {
+ next = curr->next;
+ task = curr->task;
+ /*
+ * see exit_mm(), curr->task must not see
+ * ->task == NULL before we read ->next.
+ */
+ smp_mb();
+ curr->task = NULL;
+ wake_up_process(task);
+ }
+
+ mm->core_state = NULL;
+}
+
/*
* set_dumpable converts traditional three-value dumpable to two flags and
* stores them into mm->flags. It modifies lower two bits of mm->flags, but
@@ -1807,8 +1827,7 @@ fail_unlock:
argv_free(helper_argv);
current->fsuid = fsuid;
- complete_all(&mm->core_done);
- mm->core_state = NULL;
+ coredump_finish(mm);
fail:
return retval;
}
On Tue, 15 Jul 2008 20:21:50 +0400
Oleg Nesterov <[email protected]> wrote:
> Now that we have core_state->dumper list we can use it to wake up the
> sub-threads waiting for the coredump completion.
>
> This uglifies the code and .text grows by 47 bytes, but otoh mm_struct
> lessens by sizeof(struct completion). Also, with this change we can
> decouple exit_mm() from the coredumping code.
This conflicts with your
coredump-simplify-core_state-nr_threads-calculation.patch
fs/exec.c:
***************
*** 1597,1603 ****
struct completion *vfork_done;
int core_waiters;
- init_completion(&mm->core_done);
init_completion(&core_state->startup);
core_state->dumper.task = tsk;
core_state->dumper.next = NULL;
--- 1597,1602 ----
struct completion *vfork_done;
int core_waiters;
init_completion(&core_state->startup);
core_state->dumper.task = tsk;
core_state->dumper.next = NULL;
***************
*** 1812,1819 ****
argv_free(helper_argv);
current->fsuid = fsuid;
- complete_all(&mm->core_done);
- mm->core_state = NULL;
fail:
return retval;
}
--- 1832,1838 ----
argv_free(helper_argv);
current->fsuid = fsuid;
+ coredump_finish(mm);
fail:
return retval;
}
The second hunk is a bit worrisome. The
mm->core_state = NULL;
isn't there any more.
I have a bad feelnig that I have a coredump patch which should have
been dropped. Can you please check everything?
Current queue:
#
# coredump
#
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-kill-mm-core_done.patch
All at http://userweb.kernel.org/~akpm/mmotm/
Hi,
Oleg Nesterov <[email protected]> writes:
> Now that we have core_state->dumper list we can use it to wake up the
> sub-threads waiting for the coredump completion.
>
> This uglifies the code and .text grows by 47 bytes, but otoh mm_struct
> lessens by sizeof(struct completion). Also, with this change we can
> decouple exit_mm() from the coredumping code.
>
> Signed-off-by: Oleg Nesterov <[email protected]>
>
> include/linux/mm_types.h | 4 +---
> kernel/exit.c | 8 +++++++-
> fs/exec.c | 25 ++++++++++++++++++++++---
> 3 files changed, 30 insertions(+), 7 deletions(-)
>
> --- 26-rc2/include/linux/mm_types.h~5_KILL_CORE_DONE 2008-07-13 18:28:36.000000000 +0400
> +++ 26-rc2/include/linux/mm_types.h 2008-07-15 17:06:58.000000000 +0400
> @@ -229,9 +229,7 @@ struct mm_struct {
>
> unsigned long flags; /* Must use atomic bitops to access the bits */
>
> - /* coredumping support */
> - struct core_state *core_state;
> - struct completion core_done;
> + struct core_state *core_state; /* coredumping support */
>
> /* aio bits */
> rwlock_t ioctx_list_lock; /* aio lock */
> --- 26-rc2/kernel/exit.c~5_KILL_CORE_DONE 2008-07-13 19:58:19.000000000 +0400
> +++ 26-rc2/kernel/exit.c 2008-07-15 17:06:58.000000000 +0400
> @@ -680,7 +680,13 @@ static void exit_mm(struct task_struct *
> if (atomic_dec_and_test(&core_state->nr_threads))
> complete(&core_state->startup);
>
> - wait_for_completion(&mm->core_done);
> + for (;;) {
> + set_task_state(tsk, TASK_UNINTERRUPTIBLE);
> + if (!self.task) /* see coredump_finish() */
kernel/exit.c: In function `exit_mm':
kernel/exit.c:686: error: `self' undeclared (first use in this function)
kernel/exit.c:686: error: (Each undeclared identifier is reported only once
kernel/exit.c:686: error: for each function it appears in.)
make[1]: *** [kernel/exit.o] Error 1
Hannes
It is indeed ugly. I think the place to start is with moving all the
coredump code out of exit_mm() into a new subfunction that is just passed
the mm pointer, and doing the same with coredump_finish() as you've done,
but leaving the completion logic inside those functions the same. If all
references to the core_* fields in mm_struct are inside coredump_*()
functions, then that is a good basis for the future cleanups.
Thanks,
Roland
On 07/20, Johannes Weiner wrote:
>
> Oleg Nesterov <[email protected]> writes:
>
> > --- 26-rc2/kernel/exit.c~5_KILL_CORE_DONE 2008-07-13 19:58:19.000000000 +0400
> > +++ 26-rc2/kernel/exit.c 2008-07-15 17:06:58.000000000 +0400
> > @@ -680,7 +680,13 @@ static void exit_mm(struct task_struct *
> > if (atomic_dec_and_test(&core_state->nr_threads))
> > complete(&core_state->startup);
> >
> > - wait_for_completion(&mm->core_done);
> > + for (;;) {
> > + set_task_state(tsk, TASK_UNINTERRUPTIBLE);
> > + if (!self.task) /* see coredump_finish() */
>
> kernel/exit.c: In function `exit_mm':
> kernel/exit.c:686: error: `self' undeclared (first use in this function)
> kernel/exit.c:686: error: (Each undeclared identifier is reported only once
> kernel/exit.c:686: error: for each function it appears in.)
> make[1]: *** [kernel/exit.o] Error 1
This is on top of other patches in -mm tree,
coredump-zap_threads-comments-use-while_each_thread.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
Oleg.
On 07/19, Roland McGrath wrote:
>
> It is indeed ugly. I think the place to start is with moving all the
> coredump code out of exit_mm() into a new subfunction that is just passed
> the mm pointer, and doing the same with coredump_finish() as you've done,
> but leaving the completion logic inside those functions the same.
The next patch does this.
This patch goes first because it kills the last field in mm_struct which
is needed for the coredump code, so new new function (exit_coredump) doesn't
need the mm pointer at all.
Oleg.
Hi,
Oleg Nesterov <[email protected]> writes:
> On 07/20, Johannes Weiner wrote:
>>
>> Oleg Nesterov <[email protected]> writes:
>>
>> > --- 26-rc2/kernel/exit.c~5_KILL_CORE_DONE 2008-07-13 19:58:19.000000000 +0400
>> > +++ 26-rc2/kernel/exit.c 2008-07-15 17:06:58.000000000 +0400
>> > @@ -680,7 +680,13 @@ static void exit_mm(struct task_struct *
>> > if (atomic_dec_and_test(&core_state->nr_threads))
>> > complete(&core_state->startup);
>> >
>> > - wait_for_completion(&mm->core_done);
>> > + for (;;) {
>> > + set_task_state(tsk, TASK_UNINTERRUPTIBLE);
>> > + if (!self.task) /* see coredump_finish() */
>>
>> kernel/exit.c: In function `exit_mm':
>> kernel/exit.c:686: error: `self' undeclared (first use in this function)
>> kernel/exit.c:686: error: (Each undeclared identifier is reported only once
>> kernel/exit.c:686: error: for each function it appears in.)
>> make[1]: *** [kernel/exit.o] Error 1
>
> This is on top of other patches in -mm tree,
>
> coredump-zap_threads-comments-use-while_each_thread.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
Sorry, I should have given more information.
I was building -mm directly with all these patches applied. I did not
cherry-pick this exact patch into some other tree.
But I still can not find anything defining `self' in these patches:
$ grep self coredump-*.patch \
introduce-pf_kthread-flag.patch \
kill-pf_borrowed_mm-in-favour-of-pf_kthread.patch
coredump-kill-mm-core_done.patch:+ if (!self.task) /* see coredump_finish() */
cscope finds some other definitions of self in the tree, but nothing
relevant.
Hannes
On 07/20, Johannes Weiner wrote:
>
> Oleg Nesterov <[email protected]> writes:
>
> > On 07/20, Johannes Weiner wrote:
> >>
> >> Oleg Nesterov <[email protected]> writes:
> >>
> >> > --- 26-rc2/kernel/exit.c~5_KILL_CORE_DONE 2008-07-13 19:58:19.000000000 +0400
> >> > +++ 26-rc2/kernel/exit.c 2008-07-15 17:06:58.000000000 +0400
> >> > @@ -680,7 +680,13 @@ static void exit_mm(struct task_struct *
> >> > if (atomic_dec_and_test(&core_state->nr_threads))
> >> > complete(&core_state->startup);
> >> >
> >> > - wait_for_completion(&mm->core_done);
> >> > + for (;;) {
> >> > + set_task_state(tsk, TASK_UNINTERRUPTIBLE);
> >> > + if (!self.task) /* see coredump_finish() */
> >>
> >> kernel/exit.c: In function `exit_mm':
> >> kernel/exit.c:686: error: `self' undeclared (first use in this function)
> >> kernel/exit.c:686: error: (Each undeclared identifier is reported only once
> >> kernel/exit.c:686: error: for each function it appears in.)
> >> make[1]: *** [kernel/exit.o] Error 1
> >
> > This is on top of other patches in -mm tree,
> >
> > coredump-zap_threads-comments-use-while_each_thread.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
>
> Sorry, I should have given more information.
>
> I was building -mm directly with all these patches applied. I did not
> cherry-pick this exact patch into some other tree.
>
> But I still can not find anything defining `self' in these patches:
Because it was merged into -mm before the previous 4 patches by mistake,
sorry.
Just drop this one:
http://userweb.kernel.org/~akpm/mmotm/broken-out/coredump-kill-mm-core_done.patch
Oleg.
Hi,
Oleg Nesterov <[email protected]> writes:
> On 07/20, Johannes Weiner wrote:
>>
>> Oleg Nesterov <[email protected]> writes:
>>
>> > On 07/20, Johannes Weiner wrote:
>> >>
>> >> Oleg Nesterov <[email protected]> writes:
>> >>
>> >> > --- 26-rc2/kernel/exit.c~5_KILL_CORE_DONE 2008-07-13 19:58:19.000000000 +0400
>> >> > +++ 26-rc2/kernel/exit.c 2008-07-15 17:06:58.000000000 +0400
>> >> > @@ -680,7 +680,13 @@ static void exit_mm(struct task_struct *
>> >> > if (atomic_dec_and_test(&core_state->nr_threads))
>> >> > complete(&core_state->startup);
>> >> >
>> >> > - wait_for_completion(&mm->core_done);
>> >> > + for (;;) {
>> >> > + set_task_state(tsk, TASK_UNINTERRUPTIBLE);
>> >> > + if (!self.task) /* see coredump_finish() */
>> >>
>> >> kernel/exit.c: In function `exit_mm':
>> >> kernel/exit.c:686: error: `self' undeclared (first use in this function)
>> >> kernel/exit.c:686: error: (Each undeclared identifier is reported only once
>> >> kernel/exit.c:686: error: for each function it appears in.)
>> >> make[1]: *** [kernel/exit.o] Error 1
>> >
>> > This is on top of other patches in -mm tree,
>> >
>> > coredump-zap_threads-comments-use-while_each_thread.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
>>
>> Sorry, I should have given more information.
>>
>> I was building -mm directly with all these patches applied. I did not
>> cherry-pick this exact patch into some other tree.
>>
>> But I still can not find anything defining `self' in these patches:
>
> Because it was merged into -mm before the previous 4 patches by mistake,
> sorry.
>
> Just drop this one:
>
> http://userweb.kernel.org/~akpm/mmotm/broken-out/coredump-kill-mm-core_done.patch
Alright, thanks!
Hannes