The patch titled
Subject: mm/page_isolation: fix potential warning from user
has been added to the -mm tree. Its filename is
mm-page_isolation-fix-potential-warning-from-user.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-page_isolation-fix-potential-warning-from-user.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-page_isolation-fix-potential-warning-from-user.patch
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------------------------------------------------------
From: Qian Cai <cai@xxxxxx>
Subject: mm/page_isolation: fix potential warning from user
It makes sense to call the WARN_ON_ONCE(zone_idx(zone) == ZONE_MOVABLE)
from start_isolate_page_range(), but should avoid triggering it from
userspace, i.e, from is_mem_section_removable() because it could crash the
system by a non-root user if warn_on_panic is set.
While at it, simplify the code a bit by removing an unnecessary jump
label.
Link: http://lkml.kernel.org/r/20200120163915.1469-1-cai@xxxxxx
Signed-off-by: Qian Cai <cai@xxxxxx>
Suggested-by: Michal Hocko <mhocko@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 11 ++++-------
mm/page_isolation.c | 18 +++++++++++-------
2 files changed, 15 insertions(+), 14 deletions(-)
--- a/mm/page_alloc.c~mm-page_isolation-fix-potential-warning-from-user
+++ a/mm/page_alloc.c
@@ -8231,7 +8231,7 @@ struct page *has_unmovable_pages(struct
if (is_migrate_cma(migratetype))
return NULL;
- goto unmovable;
+ return page;
}
for (; iter < pageblock_nr_pages; iter++) {
@@ -8241,7 +8241,7 @@ struct page *has_unmovable_pages(struct
page = pfn_to_page(pfn + iter);
if (PageReserved(page))
- goto unmovable;
+ return page;
/*
* If the zone is movable and we have ruled out all reserved
@@ -8261,7 +8261,7 @@ struct page *has_unmovable_pages(struct
unsigned int skip_pages;
if (!hugepage_migration_supported(page_hstate(head)))
- goto unmovable;
+ return page;
skip_pages = compound_nr(head) - (page - head);
iter += skip_pages - 1;
@@ -8303,12 +8303,9 @@ struct page *has_unmovable_pages(struct
* is set to both of a memory hole page and a _used_ kernel
* page at boot.
*/
- goto unmovable;
+ return page;
}
return NULL;
-unmovable:
- WARN_ON_ONCE(zone_idx(zone) == ZONE_MOVABLE);
- return pfn_to_page(pfn + iter);
}
#ifdef CONFIG_CONTIG_ALLOC
--- a/mm/page_isolation.c~mm-page_isolation-fix-potential-warning-from-user
+++ a/mm/page_isolation.c
@@ -54,14 +54,18 @@ static int set_migratetype_isolate(struc
out:
spin_unlock_irqrestore(&zone->lock, flags);
- if (!ret)
+ if (!ret) {
drain_all_pages(zone);
- else if ((isol_flags & REPORT_FAILURE) && unmovable)
- /*
- * printk() with zone->lock held will guarantee to trigger a
- * lockdep splat, so defer it here.
- */
- dump_page(unmovable, "unmovable page");
+ } else {
+ WARN_ON_ONCE(zone_idx(zone) == ZONE_MOVABLE);
+
+ if ((isol_flags & REPORT_FAILURE) && unmovable)
+ /*
+ * printk() with zone->lock held will likely trigger a
+ * lockdep splat, so defer it here.
+ */
+ dump_page(unmovable, "unmovable page");
+ }
return ret;
}
_
Patches currently in -mm which might be from cai@xxxxxx are
mm-hotplug-silence-a-lockdep-splat-with-printk.patch
mm-page_isolation-fix-potential-warning-from-user.patch
