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commit 2e3b89ed93dfd266d4061445bb04b20574461539
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Author: Dave Anderson <anderson@redhat.com>
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Date: Fri Jul 17 10:41:32 2015 -0400
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Fix for the "kmem -s <address>", "bt -F[F]", and "rd -S[S]"
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options in kernels configured with CONFIG_SLUB. Without the patch,
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if a referenced slab object address comes from a slab cache that
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utilizes a multiple-page slab, and the object is located within
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a tail page of that slab cache, it will not be recognized as a slab
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object. The "bt -F[F]" and "rd -S[S]" options will just show the
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object address, and the "kmem -s <address>" object will indicate
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"kmem: address is not allocated in slab subsystem: <address>".
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This bug is a regression that was introduced in crash-7.1.0 by commit
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8b2cb365d7fb139e77cedd80d4061332099ed382, which addressed a bug where
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stale slab object addresses were incorrectly being recognized as
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valid slab objects.
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(anderson@redhat.com)
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diff --git a/memory.c b/memory.c
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index fa2970c..a7988fd 100644
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--- a/memory.c
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+++ b/memory.c
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@@ -9103,8 +9103,16 @@ vaddr_to_kmem_cache(ulong vaddr, char *buf, int verbose)
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readmem(page+OFFSET(page_flags), KVADDR,
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&page_flags, sizeof(ulong), "page.flags",
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FAULT_ON_ERROR);
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- if (!(page_flags & (1 << vt->PG_slab)))
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- return NULL;
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+ if (!(page_flags & (1 << vt->PG_slab))) {
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+ if (vt->flags & KMALLOC_SLUB) {
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+ readmem(compound_head(page)+OFFSET(page_flags), KVADDR,
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+ &page_flags, sizeof(ulong), "page.flags",
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+ FAULT_ON_ERROR);
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+ if (!(page_flags & (1 << vt->PG_slab)))
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+ return NULL;
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+ } else
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+ return NULL;
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+ }
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}
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if ((vt->flags & KMALLOC_SLUB) ||
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