From: Oleksandr Natalenko <[email protected]>
Do the very same trick as we already do since 04f5866e41fb. KSM hints
will require locking mmap_sem for write since they modify vm_flags, so
for remote KSM hinting this additional check is needed.
Reviewed-by: Suren Baghdasaryan <[email protected]>
Signed-off-by: Oleksandr Natalenko <[email protected]>
Signed-off-by: Minchan Kim <[email protected]>
---
mm/madvise.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/mm/madvise.c b/mm/madvise.c
index e794367f681e..e77c6c1fad34 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -1118,6 +1118,8 @@ int do_madvise(struct task_struct *target_task, struct mm_struct *mm,
if (write) {
if (down_write_killable(&mm->mmap_sem))
return -EINTR;
+ if (current->mm != mm && !mmget_still_valid(mm))
+ goto skip_mm;
} else {
down_read(&mm->mmap_sem);
}
@@ -1169,6 +1171,7 @@ int do_madvise(struct task_struct *target_task, struct mm_struct *mm,
}
out:
blk_finish_plug(&plug);
+skip_mm:
if (write)
up_write(&mm->mmap_sem);
else
--
2.25.0.265.gbab2e86ba0-goog
On 3/2/20 8:36 PM, Minchan Kim wrote:
> From: Oleksandr Natalenko <[email protected]>
>
> Do the very same trick as we already do since 04f5866e41fb. KSM hints
> will require locking mmap_sem for write since they modify vm_flags, so
> for remote KSM hinting this additional check is needed.
>
> Reviewed-by: Suren Baghdasaryan <[email protected]>
> Signed-off-by: Oleksandr Natalenko <[email protected]>
> Signed-off-by: Minchan Kim <[email protected]>
> ---
> mm/madvise.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/mm/madvise.c b/mm/madvise.c
> index e794367f681e..e77c6c1fad34 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -1118,6 +1118,8 @@ int do_madvise(struct task_struct *target_task, struct mm_struct *mm,
> if (write) {
> if (down_write_killable(&mm->mmap_sem))
> return -EINTR;
> + if (current->mm != mm && !mmget_still_valid(mm))
> + goto skip_mm;
This will return 0, is that correct? Shoudln't there be a similar error e.g. as
when finding the task by pid fails (-ESRCH ?), because IIUC the task here is
going away and dumping the core?
> } else {
> down_read(&mm->mmap_sem);
> }
> @@ -1169,6 +1171,7 @@ int do_madvise(struct task_struct *target_task, struct mm_struct *mm,
> }
> out:
> blk_finish_plug(&plug);
> +skip_mm:
> if (write)
> up_write(&mm->mmap_sem);
> else
>
Hello.
On Fri, Mar 06, 2020 at 01:52:07PM +0100, Vlastimil Babka wrote:
> > diff --git a/mm/madvise.c b/mm/madvise.c
> > index e794367f681e..e77c6c1fad34 100644
> > --- a/mm/madvise.c
> > +++ b/mm/madvise.c
> > @@ -1118,6 +1118,8 @@ int do_madvise(struct task_struct *target_task, struct mm_struct *mm,
> > if (write) {
> > if (down_write_killable(&mm->mmap_sem))
> > return -EINTR;
> > + if (current->mm != mm && !mmget_still_valid(mm))
> > + goto skip_mm;
>
> This will return 0, is that correct? Shoudln't there be a similar error e.g. as
> when finding the task by pid fails (-ESRCH ?), because IIUC the task here is
> going away and dumping the core?
Yeah.
Something like this then:
===
diff --git a/mm/madvise.c b/mm/madvise.c
index 48d1da08c160..7ed2f4d13924 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -1122,6 +1122,10 @@ int do_madvise(struct task_struct *target_task, struct mm_struct *mm,
if (write) {
if (down_write_killable(&mm->mmap_sem))
return -EINTR;
+ if (current->mm != mm && !mmget_still_valid(mm)) {
+ error = -ESRCH;
+ goto skip_mm;
+ }
} else {
down_read(&mm->mmap_sem);
}
@@ -1173,6 +1177,7 @@ int do_madvise(struct task_struct *target_task, struct mm_struct *mm,
}
out:
blk_finish_plug(&plug);
+skip_mm:
if (write)
up_write(&mm->mmap_sem);
else
===
?
>
> > } else {
> > down_read(&mm->mmap_sem);
> > }
> > @@ -1169,6 +1171,7 @@ int do_madvise(struct task_struct *target_task, struct mm_struct *mm,
> > }
> > out:
> > blk_finish_plug(&plug);
> > +skip_mm:
> > if (write)
> > up_write(&mm->mmap_sem);
> > else
> >
>
--
Best regards,
Oleksandr Natalenko (post-factum)
Principal Software Maintenance Engineer
On 3/6/20 2:03 PM, Oleksandr Natalenko wrote:
> Hello.
>
> On Fri, Mar 06, 2020 at 01:52:07PM +0100, Vlastimil Babka wrote:
>> > diff --git a/mm/madvise.c b/mm/madvise.c
>> > index e794367f681e..e77c6c1fad34 100644
>> > --- a/mm/madvise.c
>> > +++ b/mm/madvise.c
>> > @@ -1118,6 +1118,8 @@ int do_madvise(struct task_struct *target_task, struct mm_struct *mm,
>> > if (write) {
>> > if (down_write_killable(&mm->mmap_sem))
>> > return -EINTR;
>> > + if (current->mm != mm && !mmget_still_valid(mm))
>> > + goto skip_mm;
>>
>> This will return 0, is that correct? Shoudln't there be a similar error e.g. as
>> when finding the task by pid fails (-ESRCH ?), because IIUC the task here is
>> going away and dumping the core?
>
> Yeah.
>
> Something like this then:
>
> ===
> diff --git a/mm/madvise.c b/mm/madvise.c
> index 48d1da08c160..7ed2f4d13924 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -1122,6 +1122,10 @@ int do_madvise(struct task_struct *target_task, struct mm_struct *mm,
> if (write) {
> if (down_write_killable(&mm->mmap_sem))
> return -EINTR;
> + if (current->mm != mm && !mmget_still_valid(mm)) {
> + error = -ESRCH;
> + goto skip_mm;
> + }
> } else {
> down_read(&mm->mmap_sem);
> }
> @@ -1173,6 +1177,7 @@ int do_madvise(struct task_struct *target_task, struct mm_struct *mm,
> }
> out:
> blk_finish_plug(&plug);
> +skip_mm:
> if (write)
> up_write(&mm->mmap_sem);
> else
>
> ===
>
> ?
Yep, thanks.
On Fri, Mar 06, 2020 at 05:03:50PM +0100, Vlastimil Babka wrote:
> On 3/6/20 2:03 PM, Oleksandr Natalenko wrote:
> > Hello.
> >
> > On Fri, Mar 06, 2020 at 01:52:07PM +0100, Vlastimil Babka wrote:
> >> > diff --git a/mm/madvise.c b/mm/madvise.c
> >> > index e794367f681e..e77c6c1fad34 100644
> >> > --- a/mm/madvise.c
> >> > +++ b/mm/madvise.c
> >> > @@ -1118,6 +1118,8 @@ int do_madvise(struct task_struct *target_task, struct mm_struct *mm,
> >> > if (write) {
> >> > if (down_write_killable(&mm->mmap_sem))
> >> > return -EINTR;
> >> > + if (current->mm != mm && !mmget_still_valid(mm))
> >> > + goto skip_mm;
> >>
> >> This will return 0, is that correct? Shoudln't there be a similar error e.g. as
> >> when finding the task by pid fails (-ESRCH ?), because IIUC the task here is
> >> going away and dumping the core?
> >
> > Yeah.
> >
> > Something like this then:
> >
> > ===
> > diff --git a/mm/madvise.c b/mm/madvise.c
> > index 48d1da08c160..7ed2f4d13924 100644
> > --- a/mm/madvise.c
> > +++ b/mm/madvise.c
> > @@ -1122,6 +1122,10 @@ int do_madvise(struct task_struct *target_task, struct mm_struct *mm,
> > if (write) {
> > if (down_write_killable(&mm->mmap_sem))
> > return -EINTR;
> > + if (current->mm != mm && !mmget_still_valid(mm)) {
> > + error = -ESRCH;
> > + goto skip_mm;
> > + }
> > } else {
> > down_read(&mm->mmap_sem);
> > }
> > @@ -1173,6 +1177,7 @@ int do_madvise(struct task_struct *target_task, struct mm_struct *mm,
> > }
> > out:
> > blk_finish_plug(&plug);
> > +skip_mm:
> > if (write)
> > up_write(&mm->mmap_sem);
> > else
> >
> > ===
> >
> > ?
>
> Yep, thanks.
>
Minchan, shall you take this change into the next submission, or you'd
prefer me sending it to you as a new patch?
--
Best regards,
Oleksandr Natalenko (post-factum)
Principal Software Maintenance Engineer
On Mon, Mar 09, 2020 at 01:30:45PM +0100, Oleksandr Natalenko wrote:
> On Fri, Mar 06, 2020 at 05:03:50PM +0100, Vlastimil Babka wrote:
> > On 3/6/20 2:03 PM, Oleksandr Natalenko wrote:
> > > Hello.
> > >
> > > On Fri, Mar 06, 2020 at 01:52:07PM +0100, Vlastimil Babka wrote:
> > >> > diff --git a/mm/madvise.c b/mm/madvise.c
> > >> > index e794367f681e..e77c6c1fad34 100644
> > >> > --- a/mm/madvise.c
> > >> > +++ b/mm/madvise.c
> > >> > @@ -1118,6 +1118,8 @@ int do_madvise(struct task_struct *target_task, struct mm_struct *mm,
> > >> > if (write) {
> > >> > if (down_write_killable(&mm->mmap_sem))
> > >> > return -EINTR;
> > >> > + if (current->mm != mm && !mmget_still_valid(mm))
> > >> > + goto skip_mm;
> > >>
> > >> This will return 0, is that correct? Shoudln't there be a similar error e.g. as
> > >> when finding the task by pid fails (-ESRCH ?), because IIUC the task here is
> > >> going away and dumping the core?
> > >
> > > Yeah.
> > >
> > > Something like this then:
> > >
> > > ===
> > > diff --git a/mm/madvise.c b/mm/madvise.c
> > > index 48d1da08c160..7ed2f4d13924 100644
> > > --- a/mm/madvise.c
> > > +++ b/mm/madvise.c
> > > @@ -1122,6 +1122,10 @@ int do_madvise(struct task_struct *target_task, struct mm_struct *mm,
> > > if (write) {
> > > if (down_write_killable(&mm->mmap_sem))
> > > return -EINTR;
> > > + if (current->mm != mm && !mmget_still_valid(mm)) {
> > > + error = -ESRCH;
> > > + goto skip_mm;
> > > + }
> > > } else {
> > > down_read(&mm->mmap_sem);
> > > }
> > > @@ -1173,6 +1177,7 @@ int do_madvise(struct task_struct *target_task, struct mm_struct *mm,
> > > }
> > > out:
> > > blk_finish_plug(&plug);
> > > +skip_mm:
> > > if (write)
> > > up_write(&mm->mmap_sem);
> > > else
> > >
> > > ===
> > >
> > > ?
> >
> > Yep, thanks.
> >
>
> Minchan, shall you take this change into the next submission, or you'd
> prefer me sending it to you as a new patch?
I should send patchset again so I will take it.
Thanks!