+ mm-vmallocc-add-an-error-message-if-two-areas-overlap.patch added to -mm tree

[akpm@linux-foundation.org]

The patch titled
     Subject: mm/vmalloc.c: add an error message if two areas overlap
has been added to the -mm tree.  Its filename is
     mm-vmallocc-add-an-error-message-if-two-areas-overlap.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/mm-vmallocc-add-an-error-message-if-two-areas-overlap.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/mm-vmallocc-add-an-error-message-if-two-areas-overlap.patch

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------------------------------------------------------
From: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Subject: mm/vmalloc.c: add an error message if two areas overlap

Before triggering a BUG() it would be useful to understand how two areas
overlap between each other.  Print information about start/end addresses
of both VAs and their addresses.

For example if both are identical it could mean double free.

Link: http://lkml.kernel.org/r/20200710194443.2984-1-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/vmalloc.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/mm/vmalloc.c~mm-vmallocc-add-an-error-message-if-two-areas-overlap
+++ a/mm/vmalloc.c
@@ -550,8 +550,13 @@ find_va_links(struct vmap_area *va,
 		else if (va->va_end > tmp_va->va_start &&
 				va->va_start >= tmp_va->va_end)
 			link = &(*link)->rb_right;
-		else
+		else {
+			pr_err("Overlaps: 0x%px(0x%lx-0x%lx), 0x%px(0x%lx-0x%lx)\n",
+				va, va->va_start, va->va_end, tmp_va,
+				tmp_va->va_start, tmp_va->va_end);
+
 			BUG();
+		}
 	} while (*link);
 
 	*parent = &tmp_va->rb_node;
_

Patches currently in -mm which might be from urezki@gmail.com are

mm-vmalloc-simplify-merge_or_add_vmap_area-func.patch
mm-vmalloc-simplify-augment_tree_propagate_check-func.patch
mm-vmalloc-switch-to-propagate-callback.patch
mm-vmalloc-update-the-header-about-kva-rework.patch
mm-vmallocc-add-an-error-message-if-two-areas-overlap.patch