Re: [PATCH v3 0/5] HWpoison: further fixes and cleanups

[osalvador]

On 2020-09-16 18:30, osalvador@xxxxxxx wrote:
> On 2020-09-16 16:46, Aristeu Rozanski wrote:
> > Hi Oscar,
> >
> > On Wed, Sep 16, 2020 at 04:09:30PM +0200, Oscar Salvador wrote:
> > > On Wed, Sep 16, 2020 at 09:53:58AM -0400, Aristeu Rozanski wrote:
> > > Can you try the other patch I posted in response to Naoya?
> >
> > Same thing:
> >
> > [  369.195056] Soft offlining pfn 0x3fb5bf at process virtual address
> > 0x7ffc84350000
> > [  369.195073] page:000000002bb131e4 refcount:1 mapcount:0
> > mapping:0000000000000000 index:0x7ffc8435 pfn:0x3fb5bf
> > [  369.195080] anon flags:
> > 0x3ffff80008000e(referenced|uptodate|dirty|swapbacked)
> > [  369.202131] raw: 003ffff80008000e 5deadbeef0000100 5deadbeef0000122
> > c000003fda1c7431
> > [  369.202137] raw: 000000007ffc8435 0000000000000000 00000001ffffffff
> > c000003fd63af000
> > [  369.202141] page dumped because: page_handle_poison
> > [  369.202145] page->mem_cgroup:c000003fd63af000
> > [  369.215055] page_handle_poison: hugepage_or_freepage failed�n
> > [  369.215057] __soft_offline_page: page_handle_poison -EBUSY
> > [  369.215068] page:000000002bb131e4 refcount:3 mapcount:0
> > mapping:00000000f6ca3f32 index:0x5c pfn:0x3fb5bf
> > [  369.215110] aops:xfs_address_space_operations [xfs] ino:49f9c5f
> > dentry name:"messages"
> > [  369.215117] flags: 0x3ffff800002008(dirty|private)
> > [  369.215121] raw: 003ffff800002008 5deadbeef0000100 5deadbeef0000122
> > c000003fadd3daa8
> > [  369.215127] raw: 000000000000005c c000003fd9497c20 00000003ffffffff
> > c000003fd1143000
> > [  369.215132] page dumped because: __soft_offline_page after migrate
> > [  369.215136] page->mem_cgroup:c000003fd1143000
>
>
> Ok, this is something different.
> The race you saw previously is kinda normal as there is a race window
> between spotting a freepage and taking it off the buddy freelists.
> The retry patch should help there.
>
> The issue you are seeing right here is due to the call to
> page_handle_poison in __soft_offline_page being wrong, as we pass
> hugepage_or_freepage = true inconditionally, which is wrong.
>
> Should be:

Fat fingers, sorry:

Ok, this is something different.
The race you saw previously is kinda normal as there is a race window 
between spotting a freepage and taking it off the buddy freelists.
The retry patch should help there.

The issue you are seeing right here is due to the call to 
page_handle_poison in __soft_offline_page being wrong, as we pass 
hugepage_or_freepage = true inconditionally, which is wrong.
I think it was caused during rebasing.

Should be:

@@ -1858,8 +1903,11 @@ static int __soft_offline_page(struct page *page)
                if (!ret) {
                        bool release = !huge;

-                       if (!page_handle_poison(page, true, release))
+                       if (!page_handle_poison(page, huge, release)) {
+                               pr_info("%s: page_handle_poison 
-EBUSY\n", __func__);
+                               dump_page(page, "__soft_offline_page 
after migrate");
                                ret = -EBUSY;
+                       }

Could you try that on top please?

I am away from my laptop now but I will be taking a look later today.

thanks