Re: [Xen-devel] [RFC PATCH] mm, oom: distinguish blockable mode for mmu notifiers

[Leon Romanovsky <leon@xxxxxxxxxx>]

On Wed, Jul 11, 2018 at 11:03:53AM +0200, Michal Hocko wrote:
> On Tue 10-07-18 19:20:20, Leon Romanovsky wrote:
> > On Tue, Jul 10, 2018 at 04:14:10PM +0200, Michal Hocko wrote:
> > > On Tue 10-07-18 16:40:40, Leon Romanovsky wrote:
> > > > On Mon, Jul 09, 2018 at 02:29:08PM +0200, Michal Hocko wrote:
> > > > > On Wed 27-06-18 09:44:21, Michal Hocko wrote:
> > > > > > This is the v2 of RFC based on the feedback I've received so far. 
> > > > > > The
> > > > > > code even compiles as a bonus ;) I haven't runtime tested it yet, 
> > > > > > mostly
> > > > > > because I have no idea how.
> > > > > >
> > > > > > Any further feedback is highly appreciated of course.
> > > > >
> > > > > Any other feedback before I post this as non-RFC?
> > > >
> > > > From mlx5 perspective, who is primary user of umem_odp.c your change 
> > > > looks ok.
> > >
> > > Can I assume your Acked-by?
> >
> > I didn't have a chance to test it because it applies on our rdma-next, but
> > fails to compile.
>
> What is the compilation problem? Is it caused by the patch or some other
> unrelated changed?

Thanks for pushing me to take a look on it.
Your patch needs the following hunk to properly compile at least on my system.

I'll take it to our regression.

diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index 369867501bed..1f364a157097 100644
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -155,9 +155,9 @@ struct mmu_notifier_ops {
         * cannot block, mmu_notifier_ops.flags should have
         * MMU_INVALIDATE_DOES_NOT_BLOCK set.
         */
-       void (*invalidate_range_start)(struct mmu_notifier *mn,
+       int (*invalidate_range_start)(struct mmu_notifier *mn,
                                       struct mm_struct *mm,
-                                      unsigned long start, unsigned long end);
+                                      unsigned long start, unsigned long end, 
bool blockable);
        void (*invalidate_range_end)(struct mmu_notifier *mn,
                                     struct mm_struct *mm,
                                     unsigned long start, unsigned long end);
@@ -229,7 +229,7 @@ extern int __mmu_notifier_test_young(struct mm_struct *mm,
                                     unsigned long address);
 extern void __mmu_notifier_change_pte(struct mm_struct *mm,
                                      unsigned long address, pte_t pte);
-extern void __mmu_notifier_invalidate_range_start(struct mm_struct *mm,
+extern int __mmu_notifier_invalidate_range_start(struct mm_struct *mm,
                                  unsigned long start, unsigned long end,
                                  bool blockable);
 extern void __mmu_notifier_invalidate_range_end(struct mm_struct *mm,
diff --git a/include/linux/oom.h b/include/linux/oom.h
index 6adac113e96d..92f70e4c6252 100644
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -95,7 +95,7 @@ static inline int check_stable_address_space(struct mm_struct 
*mm)
        return 0;
 }

-void __oom_reap_task_mm(struct mm_struct *mm);
+bool __oom_reap_task_mm(struct mm_struct *mm);

 extern unsigned long oom_badness(struct task_struct *p,
                struct mem_cgroup *memcg, const nodemask_t *nodemask,
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 7e0c6e78ae5c..7c7bd6f3298e 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -1,6 +1,6 @@
 /*
  *  linux/mm/oom_kill.c
- *
+ *
  *  Copyright (C)  1998,2000  Rik van Riel
  *     Thanks go out to Claus Fischer for some serious inspiration and
  *     for goading me into coding this file...
@@ -569,7 +569,7 @@ static bool oom_reap_task_mm(struct task_struct *tsk, 
struct mm_struct *mm)
        if (!__oom_reap_task_mm(mm)) {
                up_read(&mm->mmap_sem);
                ret = false;
-               goto out_unlock;
+               goto unlock_oom;
        }

        pr_info("oom_reaper: reaped process %d (%s), now anon-rss:%lukB, 
file-rss:%lukB, shmem-rss:%lukB\n",

Thanks

> --
> Michal Hocko
> SUSE Labs

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