From: Yang Shi <shy828301@gmail.com>
To: Peter Xu <peterx@redhat.com>
Cc: "HORIGUCHI NAOYA(堀口 直也)" <naoya.horiguchi@nec.com>,
"Hugh Dickins" <hughd@google.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
"Matthew Wilcox" <willy@infradead.org>,
"Oscar Salvador" <osalvador@suse.de>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Linux MM" <linux-mm@kvack.org>,
"Linux FS-devel Mailing List" <linux-fsdevel@vger.kernel.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
Subject: Re: [v3 PATCH 2/5] mm: filemap: check if THP has hwpoisoned subpage for PMD page fault
Date: Thu, 7 Oct 2021 14:28:35 -0700 [thread overview]
Message-ID: <CAHbLzkqm_Os8TLXgbkL-oxQVsQqRbtmjdMdx0KxNke8mUF1mWA@mail.gmail.com> (raw)
In-Reply-To: <CAHbLzkp8oO9qvDN66_ALOqNrUDrzHH7RZc3G5GQ1pxz8qXJjqw@mail.gmail.com>
On Wed, Oct 6, 2021 at 4:57 PM Yang Shi <shy828301@gmail.com> wrote:
>
> On Wed, Oct 6, 2021 at 1:15 PM Peter Xu <peterx@redhat.com> wrote:
> >
> > On Thu, Sep 30, 2021 at 02:53:08PM -0700, Yang Shi wrote:
> > > @@ -1148,8 +1148,12 @@ static int __get_hwpoison_page(struct page *page)
> > > return -EBUSY;
> > >
> > > if (get_page_unless_zero(head)) {
> > > - if (head == compound_head(page))
> > > + if (head == compound_head(page)) {
> > > + if (PageTransHuge(head))
> > > + SetPageHasHWPoisoned(head);
> > > +
> > > return 1;
> > > + }
> > >
> > > pr_info("Memory failure: %#lx cannot catch tail\n",
> > > page_to_pfn(page));
> >
> > Sorry for the late comments.
> >
> > I'm wondering whether it's ideal to set this bit here, as get_hwpoison_page()
> > sounds like a pure helper to get a refcount out of a sane hwpoisoned page. I'm
> > afraid there can be side effect that we set this without being noticed, so I'm
> > also wondering we should keep it in memory_failure().
> >
> > Quotting comments for get_hwpoison_page():
> >
> > * get_hwpoison_page() takes a page refcount of an error page to handle memory
> > * error on it, after checking that the error page is in a well-defined state
> > * (defined as a page-type we can successfully handle the memor error on it,
> > * such as LRU page and hugetlb page).
> >
> > For example, I see that both unpoison_memory() and soft_offline_page() will
> > call it too, does it mean that we'll also set the bits e.g. even when we want
> > to inject an unpoison event too?
>
> unpoison_memory() should be not a problem since it will just bail out
> once THP is met as the comment says:
>
> /*
> * unpoison_memory() can encounter thp only when the thp is being
> * worked by memory_failure() and the page lock is not held yet.
> * In such case, we yield to memory_failure() and make unpoison fail.
> */
>
>
> And I think we should set the flag for soft offline too, right? The
> soft offline does set the hwpoison flag for the corrupted sub page and
> doesn't split file THP, so it should be captured by page fault as
> well. And yes for poison injection.
Err... I must be blind. The soft offline does *NOT* set hwpoison flag
for any page. So your comment does stand. The flag should be set
outside get_hwpoison_page().
>
> But your comment reminds me that get_hwpoison_page() is just called
> when !MF_COUNT_INCREASED, so it means MADV_HWPOISON still could
> escape. This needs to be covered too.
>
> BTW, I did the test with MADV_HWPOISON, but I didn't test this change
> (moving flag set after get_page_unless_zero()) since I thought it was
> just a trivial change and did overlook this case.
>
> >
> > Thanks,
> >
> > --
> > Peter Xu
> >
next prev parent reply other threads:[~2021-10-07 21:28 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-30 21:53 [RFC v3 PATCH 0/5] Solve silent data loss caused by poisoned page cache (shmem/tmpfs) Yang Shi
2021-09-30 21:53 ` [v3 PATCH 1/5] mm: hwpoison: remove the unnecessary THP check Yang Shi
2021-10-06 2:35 ` Yang Shi
2021-10-06 4:00 ` Naoya Horiguchi
2021-10-06 17:56 ` Yang Shi
2021-09-30 21:53 ` [v3 PATCH 2/5] mm: filemap: check if THP has hwpoisoned subpage for PMD page fault Yang Shi
2021-10-01 7:23 ` Naoya Horiguchi
2021-10-01 21:07 ` Yang Shi
2021-10-04 14:06 ` Kirill A. Shutemov
2021-10-04 18:17 ` Yang Shi
2021-10-04 19:41 ` Kirill A. Shutemov
2021-10-04 20:13 ` Yang Shi
2021-10-06 19:54 ` Peter Xu
2021-10-06 23:41 ` Yang Shi
2021-10-07 16:14 ` Peter Xu
2021-10-07 18:28 ` Yang Shi
2021-10-08 9:35 ` Kirill A. Shutemov
2021-10-11 22:57 ` Peter Xu
2021-10-06 20:15 ` Peter Xu
2021-10-06 23:57 ` Yang Shi
2021-10-07 16:06 ` Peter Xu
2021-10-07 18:19 ` Yang Shi
2021-10-07 20:27 ` Yang Shi
2021-10-07 21:28 ` Yang Shi [this message]
2021-10-12 0:55 ` Peter Xu
2021-10-12 1:44 ` Peter Xu
2021-10-12 18:02 ` Yang Shi
2021-10-12 22:10 ` Peter Xu
2021-10-13 2:48 ` Yang Shi
2021-10-13 3:01 ` Peter Xu
2021-10-13 3:27 ` Yang Shi
2021-10-13 3:41 ` Peter Xu
2021-10-13 21:42 ` Yang Shi
2021-10-13 23:13 ` Peter Xu
2021-10-14 6:54 ` Naoya Horiguchi
2021-10-06 20:18 ` Peter Xu
2021-10-07 2:49 ` Yang Shi
2021-11-01 19:05 ` Naresh Kamboju
2021-11-01 19:26 ` Yang Shi
2021-09-30 21:53 ` [v3 PATCH 3/5] mm: hwpoison: refactor refcount check handling Yang Shi
2021-10-06 22:01 ` Peter Xu
2021-10-07 2:47 ` Yang Shi
2021-10-07 16:18 ` Peter Xu
2021-09-30 21:53 ` [v3 PATCH 4/5] mm: shmem: don't truncate page if memory failure happens Yang Shi
2021-10-01 7:05 ` Naoya Horiguchi
2021-10-01 21:08 ` Yang Shi
2021-10-12 1:57 ` Peter Xu
2021-10-12 19:17 ` Yang Shi
2021-10-12 22:26 ` Peter Xu
2021-10-13 3:00 ` Yang Shi
2021-10-13 3:06 ` Peter Xu
2021-10-13 3:29 ` Yang Shi
2021-09-30 21:53 ` [v3 PATCH 5/5] mm: hwpoison: handle non-anonymous THP correctly Yang Shi
2021-10-01 7:06 ` Naoya Horiguchi
2021-10-01 21:09 ` Yang Shi
2021-10-13 2:40 ` [RFC v3 PATCH 0/5] Solve silent data loss caused by poisoned page cache (shmem/tmpfs) Peter Xu
2021-10-13 3:09 ` Yang Shi
2021-10-13 3:24 ` Peter Xu
2021-10-14 6:54 ` Naoya Horiguchi
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