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imf27.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Aw9qSXLT; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf27.hostedemail.com: domain of xiubli@redhat.com has no SPF policy when checking 170.10.129.124) smtp.mailfrom=xiubli@redhat.com Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Aw9qSXLT; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf27.hostedemail.com: domain of xiubli@redhat.com has no SPF policy when checking 170.10.129.124) smtp.mailfrom=xiubli@redhat.com X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 11F384001F X-Stat-Signature: 5w6s48ibkgypphq7z3ez8sqsssb6urhd X-HE-Tag: 1655768552-895585 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 6/19/22 11:11 PM, Matthew Wilcox (Oracle) wrote: > In our efforts to remove uses of PG_private, we have found folios with > the private flag clear and folio->private not-NULL. That is the root > cause behind 642d51fb0775 ("ceph: check folio PG_private bit instead > of folio->private"). It can also affect a few other filesystems that > haven't yet reported a problem. > > compaction_alloc() can return a page with uninitialised page->private, > and rather than checking all the callers of migrate_pages(), just zero > page->private after calling get_new_page(). Similarly, the tail pages > from split_huge_page() may also have an uninitialised page->private. > > Reported-by: Xiubo Li > Signed-off-by: Matthew Wilcox (Oracle) > --- > mm/huge_memory.c | 1 + > mm/migrate.c | 1 + > 2 files changed, 2 insertions(+) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index f7248002dad9..9b31a50217b5 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2377,6 +2377,7 @@ static void __split_huge_page_tail(struct page *head, int tail, > page_tail); > page_tail->mapping = head->mapping; > page_tail->index = head->index + tail; > + page_tail->private = NULL; > > /* Page flags must be visible before we make the page non-compound. */ > smp_wmb(); > diff --git a/mm/migrate.c b/mm/migrate.c > index e51588e95f57..6c1ea61f39d8 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -1106,6 +1106,7 @@ static int unmap_and_move(new_page_t get_new_page, > if (!newpage) > return -ENOMEM; > > + newpage->private = 0; > rc = __unmap_and_move(page, newpage, force, mode); > if (rc == MIGRATEPAGE_SUCCESS) > set_page_owner_migrate_reason(newpage, reason); Test this patch by reverting my previous patch for many times yesterday, and it worked well for me till now. I will test it more to see whether there are other cases could cause the crash. Tested-by: Xiubo Li -- Xiubo