commit 2e3b89ed93dfd266d4061445bb04b20574461539
Author: Dave Anderson <anderson@redhat.com>
Date:   Fri Jul 17 10:41:32 2015 -0400

    Fix for the "kmem -s <address>", "bt -F[F]", and "rd -S[S]"
    options in kernels configured with CONFIG_SLUB.  Without the patch,
    if a referenced slab object address comes from a slab cache that
    utilizes a multiple-page slab, and the object is located within
    a tail page of that slab cache, it will not be recognized as a slab
    object.  The "bt -F[F]" and "rd -S[S]" options will just show the
    object address, and the "kmem -s <address>" object will indicate
    "kmem: address is not allocated in slab subsystem: <address>".
    This bug is a regression that was introduced in crash-7.1.0 by commit
    8b2cb365d7fb139e77cedd80d4061332099ed382, which addressed a bug where
    stale slab object addresses were incorrectly being recognized as
    valid slab objects.
    (anderson@redhat.com)

diff --git a/memory.c b/memory.c
index fa2970c..a7988fd 100644
--- a/memory.c
+++ b/memory.c
@@ -9103,8 +9103,16 @@ vaddr_to_kmem_cache(ulong vaddr, char *buf, int verbose)
 		readmem(page+OFFSET(page_flags), KVADDR,
 			&page_flags, sizeof(ulong), "page.flags",
 			FAULT_ON_ERROR);
-		if (!(page_flags & (1 << vt->PG_slab)))
-			return NULL;
+		if (!(page_flags & (1 << vt->PG_slab))) {
+			if (vt->flags & KMALLOC_SLUB) {
+				readmem(compound_head(page)+OFFSET(page_flags), KVADDR,
+					&page_flags, sizeof(ulong), "page.flags",
+					FAULT_ON_ERROR);
+				if (!(page_flags & (1 << vt->PG_slab)))
+					return NULL;
+			} else
+				return NULL;
+		}
 	}
 
 	if ((vt->flags & KMALLOC_SLUB) ||