[Crash-utility] [PATCH] memory: handle kmem_cache per-node pointer layout

Linux commit 5ba6bc27b1f9 ("slab: decouple pointer to barn from kmem_cache_node") moved the kmem_cache_node pointers from kmem_cache.node[] to kmem_cache.per_node[].node. Teach the SLUB traversal code to recognize and handle both layouts. Without this, crash treats the new layout as non-NUMA and kmem -s fails while looking for the removed kmem_cache.local_node member. Signed-off-by: Harshvardhan Jha <harshvardhan.j.jha(a)oracle.com&gt; --- Testing was performed manually on x86_64 VMs: - Linux 7.1.0-rc7 with the new per_node layout: upstream crash failed with the kmem_cache_local_node invalid-offset error, while the patched crash completed kmem -s and displayed the slab-cache table. - Linux 6.18.0-rc7 with the old node[1024] layout: the patched crash completed kmem -s and displayed the slab-cache table. defs.h | 3 +++ memory.c | 39 ++++++++++++++++++++++++++++++--------- symbols.c | 6 ++++++ 3 files changed, 39 insertions(+), 9 deletions(-) diff --git a/defs.h b/defs.h index e3027e2..ccd84a0 100644 --- a/defs.h +++ b/defs.h @@ -1766,6 +1766,8 @@ struct offset_table { /* stash of commonly-used offsets */ long kmem_cache_name; long kmem_cache_list; long kmem_cache_node; + long kmem_cache_per_node; + long kmem_cache_per_node_node; long kmem_cache_cpu_slab; long page_inuse; /* long page_offset; use "old" page->offset */ @@ -2395,6 +2397,7 @@ struct size_table { /* stash of commonly-used sizes */ long rlimit; long kmem_cache; long kmem_cache_node; + long kmem_cache_per_node_ptrs; long upid; long kmem_cache_cpu; long cfs_rq; diff --git a/memory.c b/memory.c index 3f3aa27..cf26bd4 100644 --- a/memory.c +++ b/memory.c @@ -306,6 +306,7 @@ static int get_kmem_cache_list(ulong **); static int get_kmem_cache_root_list(ulong **); static int get_kmem_cache_child_list(ulong **, ulong); static int get_kmem_cache_slub_data(long, struct meminfo *); +static ulong get_kmem_cache_node_ptr(struct meminfo *, int); static ulong compound_head(ulong); static long count_partial(ulong, struct meminfo *, ulong *); static short count_cpu_partial(struct meminfo *, int); @@ -869,6 +870,9 @@ vm_init(void) MEMBER_OFFSET_INIT(kmem_cache_inuse, "kmem_cache", "inuse"); MEMBER_OFFSET_INIT(kmem_cache_align, "kmem_cache", "align"); MEMBER_OFFSET_INIT(kmem_cache_node, "kmem_cache", "node"); + MEMBER_OFFSET_INIT(kmem_cache_per_node, "kmem_cache", "per_node"); + MEMBER_OFFSET_INIT(kmem_cache_per_node_node, + "kmem_cache_per_node_ptrs", "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"); @@ -920,9 +924,16 @@ vm_init(void) if (INVALID_MEMBER(page_objects)) ANON_MEMBER_OFFSET_INIT(page_objects, "slab", "objects"); } + STRUCT_SIZE_INIT(kmem_cache_per_node_ptrs, + "kmem_cache_per_node_ptrs"); if (VALID_MEMBER(kmem_cache_node)) { ARRAY_LENGTH_INIT(len, NULL, "kmem_cache.node", NULL, 0); vt->flags |= CONFIG_NUMA; + } else if (VALID_MEMBER(kmem_cache_per_node) && + VALID_MEMBER(kmem_cache_per_node_node) && + VALID_SIZE(kmem_cache_per_node_ptrs)) { + ARRAY_LENGTH_INIT(len, NULL, "kmem_cache.per_node", NULL, 0); + vt->flags |= CONFIG_NUMA; } ARRAY_LENGTH_INIT(len, NULL, "kmem_cache.cpu_slab", NULL, 0); @@ -19460,6 +19471,22 @@ count_cpu_partial(struct meminfo *si, int cpu) return free_objects; } +static ulong +get_kmem_cache_node_ptr(struct meminfo *si, int node) +{ + char *node_addr; + + if (VALID_MEMBER(kmem_cache_node)) + node_addr = si->cache_buf + OFFSET(kmem_cache_node) + + (sizeof(void *) * node); + else + node_addr = si->cache_buf + OFFSET(kmem_cache_per_node) + + (SIZE(kmem_cache_per_node_ptrs) * node) + + OFFSET(kmem_cache_per_node_node); + + return ULONG(node_addr); +} + /* * Emulate the total count calculation done by the * slab_objects() sysfs function in slub.c. @@ -19537,9 +19564,7 @@ get_kmem_cache_slub_data(long cmd, struct meminfo *si) for (n = 0; n < vt->numnodes; n++) { if (vt->flags & CONFIG_NUMA) { nt = &vt->node_table[n]; - node_ptr = ULONG(si->cache_buf + - OFFSET(kmem_cache_node) + - (sizeof(void *) * nt->node_id)); + node_ptr = get_kmem_cache_node_ptr(si, nt->node_id); } else node_ptr = si->cache + OFFSET(kmem_cache_local_node); @@ -19709,9 +19734,7 @@ do_kmem_cache_slub(struct meminfo *si) for (n = 0; n < vt->numnodes; n++) { if (vt->flags & CONFIG_NUMA) { nt = &vt->node_table[n]; - node_ptr = ULONG(si->cache_buf + - OFFSET(kmem_cache_node) + - (sizeof(void *)* nt->node_id)); + node_ptr = get_kmem_cache_node_ptr(si, nt->node_id); } else node_ptr = si->cache + OFFSET(kmem_cache_local_node); @@ -20515,9 +20538,7 @@ slab_to_kmem_cache_node(struct meminfo *si, ulong slab_page) if (vt->flags & CONFIG_NUMA) { node = page_to_nid(slab_page); - node_ptr = ULONG(si->cache_buf + - OFFSET(kmem_cache_node) + - (sizeof(void *)*node)); + node_ptr = get_kmem_cache_node_ptr(si, node); } else node_ptr = si->cache + OFFSET(kmem_cache_local_node); diff --git a/symbols.c b/symbols.c index a7ccdb1..652fce4 100644 --- a/symbols.c +++ b/symbols.c @@ -10922,6 +10922,10 @@ dump_offset_table(char *spec, ulong makestruct) OFFSET(kmem_cache_red_left_pad)); fprintf(fp, " kmem_cache_node: %ld\n", OFFSET(kmem_cache_node)); + fprintf(fp, " kmem_cache_per_node: %ld\n", + OFFSET(kmem_cache_per_node)); + fprintf(fp, " kmem_cache_per_node_node: %ld\n", + OFFSET(kmem_cache_per_node_node)); fprintf(fp, " kmem_cache_cpu_slab: %ld\n", OFFSET(kmem_cache_cpu_slab)); fprintf(fp, " kmem_cache_cpu_partial: %ld\n", @@ -12042,6 +12046,8 @@ dump_offset_table(char *spec, ulong makestruct) SIZE(kmem_bufctl_t)); fprintf(fp, " kmem_cache: %ld\n", SIZE(kmem_cache)); fprintf(fp, " kmem_cache_node: %ld\n", SIZE(kmem_cache_node)); + fprintf(fp, " kmem_cache_per_node_ptrs: %ld\n", + SIZE(kmem_cache_per_node_ptrs)); fprintf(fp, " kmem_cache_cpu: %ld\n", SIZE(kmem_cache_cpu)); fprintf(fp, " swap_info_struct: %ld\n", -- 2.52.0