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Tsirkin" Subject: [PATCH v1 2/6] mm/page_isolation: don't dump_page(NULL) in set_migratetype_isolate() Date: Tue, 30 Jun 2020 16:26:35 +0200 Message-Id: <20200630142639.22770-3-david@redhat.com> In-Reply-To: <20200630142639.22770-1-david@redhat.com> References: <20200630142639.22770-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Rspamd-Queue-Id: 2B96A18021873 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 Content-Transfer-Encoding: quoted-printable 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: Right now, if we have two isolations racing, we might trigger the WARN_ON_ONCE() and to dump_page(NULL), dereferencing NULL. Let's just return directly. In the future, we might want to report -EAGAIN to the caller instead, as this could indicate a temporary isolation failure only. Cc: Andrew Morton Cc: Michal Hocko Cc: Michael S. Tsirkin Signed-off-by: David Hildenbrand --- mm/page_isolation.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/mm/page_isolation.c b/mm/page_isolation.c index f6d07c5f0d34d..553b49a34cf71 100644 --- a/mm/page_isolation.c +++ b/mm/page_isolation.c @@ -29,10 +29,12 @@ static int set_migratetype_isolate(struct page *page,= int migratetype, int isol_ /* * We assume the caller intended to SET migrate type to isolate. * If it is already set, then someone else must have raced and - * set it before us. Return -EBUSY + * set it before us. */ - if (is_migrate_isolate_page(page)) - goto out; + if (is_migrate_isolate_page(page)) { + spin_unlock_irqrestore(&zone->lock, flags); + return -EBUSY; + } =20 /* * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself. --=20 2.26.2