If SLAB_RED_ZONE is enabled, slub adds guard zone of sizeof(void *)
onto head of slab page (red zone padding of left of object) on v4.6 or
later.
Without this fix, like following SUPERBLK and [allocate addr] has
difference.
crash> mount
MOUNT SUPERBLK TYPE DEVNAME DIRNAME
ffff88013ae58040 ffff88013ac35698 rootfs rootfs /
[...]
crash> kmem ffff88013ac35698
CACHE NAME OBJSIZE ALLOCATED TOTAL SLABS SSIZE
ffff88013ac05bc0 kmalloc-4096 4096 118 126 18 32k
SLAB MEMORY NODE TOTAL ALLOCATED FREE
ffffea0004eb0c00 ffff88013ac30000 0 7 7 0
FREE / [ALLOCATED]
[ffff88013ac35690]
[...]
---
defs.h | 1 +
memory.c | 8 ++++++++
symbols.c | 2 ++
3 files changed, 11 insertions(+)
diff -puN memory.c~slub-red_zone-fix memory.c
--- crash-64/memory.c~slub-red_zone-fix 2017-01-30 10:21:12.123644726 +0900
+++ crash-64-hirofumi/memory.c 2017-01-30 10:21:12.127644748 +0900
@@ -723,6 +723,7 @@ vm_init(void)
MEMBER_OFFSET_INIT(kmem_cache_node, "kmem_cache", "node");
MEMBER_OFFSET_INIT(kmem_cache_cpu_slab, "kmem_cache",
"cpu_slab");
MEMBER_OFFSET_INIT(kmem_cache_list, "kmem_cache", "list");
+ MEMBER_OFFSET_INIT(kmem_cache_red_left_pad, "kmem_cache",
"red_left_pad");
MEMBER_OFFSET_INIT(kmem_cache_name, "kmem_cache", "name");
MEMBER_OFFSET_INIT(kmem_cache_flags, "kmem_cache", "flags");
MEMBER_OFFSET_INIT(kmem_cache_cpu_freelist, "kmem_cache_cpu",
"freelist");
@@ -18442,6 +18443,13 @@ do_slab_slub(struct meminfo *si, int ver
fprintf(fp, "< SLUB: free list END (%d found) >\n", i);
}
+ if (VALID_MEMBER(kmem_cache_red_left_pad)) {
+#define SLAB_RED_ZONE 0x00000400UL
+ ulong flags = ULONG(si->cache_buf + OFFSET(kmem_cache_flags));
+ ulong red_left_pad = ULONG(si->cache_buf +
OFFSET(kmem_cache_red_left_pad));
+ if (flags & SLAB_RED_ZONE)
+ vaddr += red_left_pad;
+ }
for (p = vaddr; p < vaddr + objects * si->size; p += si->size) {
hq_open();
is_free = FALSE;
diff -puN defs.h~slub-red_zone-fix defs.h
--- crash-64/defs.h~slub-red_zone-fix 2017-01-30 10:21:12.124644731 +0900
+++ crash-64-hirofumi/defs.h 2017-02-01 00:11:33.445552457 +0900
@@ -1696,6 +1696,7 @@ struct offset_table {
long kmem_cache_align;
long kmem_cache_name;
long kmem_cache_list;
+ long kmem_cache_red_left_pad;
long kmem_cache_node;
long kmem_cache_cpu_slab;
long page_inuse;
diff -puN symbols.c~slub-red_zone-fix symbols.c
--- crash-64/symbols.c~slub-red_zone-fix 2017-01-30 10:21:12.124644731
+0900
+++ crash-64-hirofumi/symbols.c 2017-02-01 00:11:33.446552463 +0900
@@ -9330,6 +9330,8 @@ dump_offset_table(char *spec, ulong make
OFFSET(kmem_cache_name));
fprintf(fp, " kmem_cache_list: %ld\n",
OFFSET(kmem_cache_list));
+ fprintf(fp, " kmem_cache_red_left_pad: %ld\n",
+ OFFSET(kmem_cache_red_left_pad));
fprintf(fp, " kmem_cache_node: %ld\n",
OFFSET(kmem_cache_node));
fprintf(fp, " kmem_cache_cpu_slab: %ld\n",
_
--
OGAWA Hirofumi <[email protected]>
--
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