11:03 p.m.
From: Kazuhito Hagio <k-hagio-ab(a)nec.com>
The following kernel commits split slab info from struct page into
struct slab in Linux 5.17.
d122019bf061 ("mm: Split slab into its own type")
07f910f9b729 ("mm: Remove slab from struct page")
Crash commit 5f390ed811b0 followed the change for SLUB, but crash still
uses the offset of page.lru inappropriately. It could happen to work
well because it was the same value as the offset of slab.slab_list until
Linux 6.1.
However, kernel commit 130d4df57390 ("mm/sl[au]b: rearrange struct slab
fields to allow larger rcu_head") in Linux 6.2-rc1 changed the offset of
slab.slab_list. As a result, without the patch, "kmem -s|-S" options
print the following errors and fail to print values correctly for
kernels configured with CONFIG_SLUB.
crash> kmem -S filp
CACHE OBJSIZE ALLOCATED TOTAL SLABS SSIZE NAME
kmem: filp: partial list slab: ffffcc650405ab88 invalid page.inuse: -1
ffff8fa0401eca00 232 1267 1792 56 8k filp
...
KMEM_CACHE_NODE NODE SLABS PARTIAL PER-CPU
ffff8fa0401cb8c0 0 56 24 8
NODE 0 PARTIAL:
SLAB MEMORY NODE TOTAL ALLOCATED FREE
kmem: filp: invalid partial list slab pointer: ffffcc650405ab88
Signed-off-by: Kazuhito Hagio <k-hagio-ab(a)nec.com>
---
defs.h | 1 +
memory.c | 16 ++++++++++------
symbols.c | 1 +
3 files changed, 12 insertions(+), 6 deletions(-)
diff --git a/defs.h b/defs.h
index 04476b3ff62e..57c1acc4e8df 100644
--- a/defs.h
+++ b/defs.h
@@ -2182,6 +2182,7 @@ struct offset_table { /* stash of commonly-used
offsets */
long blk_mq_tags_rqs;
long request_queue_hctx_table;
long percpu_counter_counters;
+ long slab_slab_list;
};
struct size_table { /* stash of commonly-used sizes */
diff --git a/memory.c b/memory.c
index 9d003713534b..d05737cc1429 100644
--- a/memory.c
+++ b/memory.c
@@ -781,6 +781,8 @@ vm_init(void)
if (INVALID_MEMBER(page_slab))
MEMBER_OFFSET_INIT(page_slab, "slab", "slab_cache");
+ MEMBER_OFFSET_INIT(slab_slab_list, "slab", "slab_list");
+
MEMBER_OFFSET_INIT(page_slab_page, "page", "slab_page");
if (INVALID_MEMBER(page_slab_page))
ANON_MEMBER_OFFSET_INIT(page_slab_page, "page", "slab_page");
@@ -19474,6 +19476,7 @@ do_node_lists_slub(struct meminfo *si, ulong node_ptr, int node)
{
ulong next, last, list_head, flags;
int first;
+ long list_off = VALID_MEMBER(slab_slab_list) ? OFFSET(slab_slab_list) :
OFFSET(page_lru);
if (!node_ptr)
return;
@@ -19487,7 +19490,7 @@ do_node_lists_slub(struct meminfo *si, ulong node_ptr, int node)
next == list_head ? " (empty)\n" : "");
first = 0;
while (next != list_head) {
- si->slab = last = next - OFFSET(page_lru);
+ si->slab = last = next - list_off;
if (first++ == 0)
fprintf(fp, " %s", slab_hdr);
@@ -19510,7 +19513,7 @@ do_node_lists_slub(struct meminfo *si, ulong node_ptr, int node)
if (!IS_KVADDR(next) ||
((next != list_head) &&
- !is_page_ptr(next - OFFSET(page_lru), NULL))) {
+ !is_page_ptr(next - list_off, NULL))) {
error(INFO,
"%s: partial list slab: %lx invalid page.lru.next: %lx\n",
si->curname, last, next);
@@ -19537,7 +19540,7 @@ do_node_lists_slub(struct meminfo *si, ulong node_ptr, int node)
next == list_head ? " (empty)\n" : "");
first = 0;
while (next != list_head) {
- si->slab = next - OFFSET(page_lru);
+ si->slab = next - list_off;
if (first++ == 0)
fprintf(fp, " %s", slab_hdr);
@@ -19754,6 +19757,7 @@ count_partial(ulong node, struct meminfo *si, ulong *free)
short inuse, objects;
ulong total_inuse;
ulong count = 0;
+ long list_off = VALID_MEMBER(slab_slab_list) ? OFFSET(slab_slab_list) :
OFFSET(page_lru);
count = 0;
total_inuse = 0;
@@ -19765,12 +19769,12 @@ count_partial(ulong node, struct meminfo *si, ulong *free)
hq_open();
while (next != list_head) {
- if (!readmem(next - OFFSET(page_lru) + OFFSET(page_inuse),
+ if (!readmem(next - list_off + OFFSET(page_inuse),
KVADDR, &inuse, sizeof(ushort), "page.inuse", RETURN_ON_ERROR)) {
hq_close();
return -1;
}
- last = next - OFFSET(page_lru);
+ last = next - list_off;
if (inuse == -1) {
error(INFO,
@@ -19796,7 +19800,7 @@ count_partial(ulong node, struct meminfo *si, ulong *free)
}
if (!IS_KVADDR(next) ||
((next != list_head) &&
- !is_page_ptr(next - OFFSET(page_lru), NULL))) {
+ !is_page_ptr(next - list_off, NULL))) {
error(INFO, "%s: partial list slab: %lx invalid page.lru.next: %lx\n",
si->curname, last, next);
break;
diff --git a/symbols.c b/symbols.c
index e279cfa68490..66158dcf1744 100644
--- a/symbols.c
+++ b/symbols.c
@@ -9700,6 +9700,7 @@ dump_offset_table(char *spec, ulong makestruct)
OFFSET(slab_inuse));
fprintf(fp, " slab_free: %ld\n",
OFFSET(slab_free));
+ fprintf(fp, " slab_slab_list: %ld\n",
OFFSET(slab_slab_list));
fprintf(fp, " kmem_cache_size: %ld\n",
OFFSET(kmem_cache_size));
--
2.31.1