12:09 a.m.
From: Kazuhito Hagio <k-hagio-ab(a)nec.com>
Kernel commit d50569612c29 ("mm: rename the 'compound_head' field in the
'struct page' to 'compound_info'") and related patches [1] changed
the
field name and its value.
Without the patch, crash prints the following warning during startup,
WARNING: SLUB: cannot determine how compound pages are linked
and "bt -F" option fails with the following error.
crash> bt -F
bt: invalid structure member offset: page_first_page
FILE: memory.c LINE: 20238 FUNCTION: compound_head()
[1] https://lore.kernel.org/all/20260227194302.274384-1-kas@kernel.org/
Signed-off-by: Kazuhito Hagio <k-hagio-ab(a)nec.com>
---
defs.h | 1 +
memory.c | 44 ++++++++++++++++++++++++++++++++++++--------
symbols.c | 1 +
3 files changed, 38 insertions(+), 8 deletions(-)
diff --git a/defs.h b/defs.h
index e3027e2b9141..88b7bbeb2372 100644
--- a/defs.h
+++ b/defs.h
@@ -2295,6 +2295,7 @@ struct offset_table { /* stash of commonly-used
offsets */
long page_compound_order;
long folio__folio_order;
long folio__flags_1;
+ long page_compound_info;
};
struct size_table { /* stash of commonly-used sizes */
diff --git a/memory.c b/memory.c
index 3f3aa274ab5a..7102e951f1d5 100644
--- a/memory.c
+++ b/memory.c
@@ -414,6 +414,7 @@ mem_init(void)
#define FOLIO_ORDER_V2 2
#define FOLIO_ORDER_V3 3
static int folio_order_version;
+static int compound_info_has_mask = FALSE;
/*
* Stash a few popular offsets and some basic kernel virtual memory
@@ -547,6 +548,7 @@ vm_init(void)
MEMBER_OFFSET_INIT(page_compound_head, "page",
"compound_head");
if (INVALID_MEMBER(page_compound_head))
ANON_MEMBER_OFFSET_INIT(page_compound_head, "page",
"compound_head");
+ MEMBER_OFFSET_INIT(page_compound_info, "page", "compound_info");
MEMBER_OFFSET_INIT(page_private, "page", "private");
MEMBER_OFFSET_INIT(page_freelist, "page", "freelist");
MEMBER_OFFSET_INIT(page_page_type, "page", "page_type");
@@ -1352,6 +1354,17 @@ vm_init(void)
} else if (CRASHDEBUG(1))
error(NOTE, "page_hash_table does not exist in this kernel\n");
+ /*
+ * on Linux 7.1 and later, zone.vmemmap_tails is defined only when
+ * CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP is enabled.
+ */
+#define is_power_of_2(n) (n - 1 < (n ^ (n - 1)))
+ if (VALID_MEMBER(page_compound_info) &&
+ is_power_of_2(SIZE(page)) && MEMBER_EXISTS("zone",
"vmemmap_tails"))
+ compound_info_has_mask = TRUE;
+ if (CRASHDEBUG(1))
+ error(NOTE, "compound_info_has_mask = %d\n", compound_info_has_mask);
+
kmem_cache_init();
page_flags_init();
@@ -5642,10 +5655,11 @@ PG_slab_flag_init(void)
}
}
- if (VALID_MEMBER(page_compound_head)) {
+ if (VALID_MEMBER(page_compound_head) || VALID_MEMBER(page_compound_info)) {
if (CRASHDEBUG(2))
fprintf(fp,
- "PG_head_tail_mask: (UNUSED): page.compound_head exists!\n");
+ "PG_head_tail_mask: (UNUSED): page.compound_head or "
+ "page.compound_info exists!\n");
} else if (vt->flags & KMALLOC_SLUB) {
/*
* PG_slab and the following are hardwired for
@@ -9858,7 +9872,8 @@ vaddr_to_kmem_cache(ulong vaddr, char *buf, int verbose)
&page_flags, sizeof(ulong), "page.flags",
FAULT_ON_ERROR);
if (!page_slab(page, page_flags)) {
- if (((vt->flags & KMALLOC_SLUB) || VALID_MEMBER(page_compound_head)) ||
+ if (((vt->flags & KMALLOC_SLUB) || VALID_MEMBER(page_compound_head) ||
+ VALID_MEMBER(page_compound_info)) ||
((vt->flags & KMALLOC_COMMON) &&
VALID_MEMBER(page_slab) && VALID_MEMBER(page_first_page))) {
readmem(compound_head(page)+OFFSET(page_flags), KVADDR,
@@ -9873,7 +9888,8 @@ vaddr_to_kmem_cache(ulong vaddr, char *buf, int verbose)
if ((vt->flags & KMALLOC_SLUB) ||
((vt->flags & KMALLOC_COMMON) && VALID_MEMBER(page_slab) &&
- (VALID_MEMBER(page_compound_head) || VALID_MEMBER(page_first_page)))) {
+ (VALID_MEMBER(page_compound_head) || VALID_MEMBER(page_compound_info) ||
+ VALID_MEMBER(page_first_page)))) {
readmem(compound_head(page)+OFFSET(page_slab),
KVADDR, &cache, sizeof(void *),
"page.slab", FAULT_ON_ERROR);
@@ -9904,7 +9920,8 @@ is_slab_overload_page(ulong vaddr, ulong *page_head, char *buf)
if ((vt->flags & SLAB_OVERLOAD_PAGE) &&
is_page_ptr(vaddr, NULL) && VALID_MEMBER(page_slab) &&
- (VALID_MEMBER(page_compound_head) || VALID_MEMBER(page_first_page))) {
+ (VALID_MEMBER(page_compound_head) || VALID_MEMBER(page_compound_info) ||
+ VALID_MEMBER(page_first_page))) {
readmem(compound_head(vaddr)+OFFSET(page_slab),
KVADDR, &cache, sizeof(void *),
"page.slab", FAULT_ON_ERROR);
@@ -9944,7 +9961,8 @@ vaddr_to_slab(ulong vaddr)
slab = 0;
- if ((vt->flags & KMALLOC_SLUB) || VALID_MEMBER(page_compound_head))
+ if ((vt->flags & KMALLOC_SLUB) || VALID_MEMBER(page_compound_head) ||
+ VALID_MEMBER(page_compound_info))
slab = compound_head(page);
else if (vt->flags & SLAB_OVERLOAD_PAGE)
slab = compound_head(page);
@@ -20222,11 +20240,21 @@ get_kmem_cache_child_list(ulong **cache_buf, ulong root)
static ulong
compound_head(ulong page)
{
- ulong flags, first_page, compound_head;
+ ulong flags, first_page, compound_head, info, mask;
first_page = page;
- if (VALID_MEMBER(page_compound_head)) {
+ if (VALID_MEMBER(page_compound_info)) {
+ if (readmem(page + OFFSET(page_compound_info), KVADDR, &info,
+ sizeof(ulong), "page.compound_info", RETURN_ON_ERROR)) {
+ if (compound_info_has_mask) {
+ mask = (info & 1) - 1;
+ mask |= info;
+ first_page = page & mask;
+ } else if (info & 1)
+ first_page = info - 1;
+ }
+ } else if (VALID_MEMBER(page_compound_head)) {
if (readmem(page+OFFSET(page_compound_head), KVADDR, &compound_head,
sizeof(ulong), "page.compound_head", RETURN_ON_ERROR)) {
if (compound_head & 1)
diff --git a/symbols.c b/symbols.c
index 03511c8cbe8c..2071bdf77819 100644
--- a/symbols.c
+++ b/symbols.c
@@ -10504,6 +10504,7 @@ dump_offset_table(char *spec, ulong makestruct)
OFFSET(page_active));
fprintf(fp, " page_compound_head: %ld\n",
OFFSET(page_compound_head));
+ fprintf(fp, " page_compound_info: %ld\n",
OFFSET(page_compound_info));
fprintf(fp, " page_private: %ld\n",
OFFSET(page_private));
fprintf(fp, " page_page_type: %ld\n",
OFFSET(page_page_type));
--
2.31.1
8:27 p.m.
New subject: [PATCH 2/2] Fix "kmem [-s]" command on Linux 7.1 and later
From: Kazuhito Hagio <k-hagio-ab(a)nec.com>
Kernel commit 5ba6bc27b1f9 ("slab: decouple pointer to barn from
kmem_cache_node") changed kmem_cache.node array into struct
kmem_cache_per_node_ptrs kmem_cache.per_node array.
Without the patch, "kmem <slab address>" and "kmem -s" option
fail with
the following error.
crash> kmem -s
kmem: invalid structure member offset: kmem_cache_local_node
FILE: memory.c LINE: 19563 FUNCTION: get_kmem_cache_slub_data()
Signed-off-by: Kazuhito Hagio <k-hagio-ab(a)nec.com>
---
This patch needs to be applied on the top of the patch [1], so 2/2.
[1] [PATCH] Fix compound_head() and "bt -F" option on Linux 7.1 and later
https://www.mail-archive.com/devel@lists.crash-utility.osci.io/msg02256.html
defs.h | 3 +++
memory.c | 19 +++++++++++++++----
symbols.c | 4 ++++
3 files changed, 22 insertions(+), 4 deletions(-)
diff --git a/defs.h b/defs.h
index 88b7bbeb2372..ef34db90113f 100644
--- a/defs.h
+++ b/defs.h
@@ -2296,6 +2296,8 @@ struct offset_table { /* stash of commonly-used
offsets */
long folio__folio_order;
long folio__flags_1;
long page_compound_info;
+ long kmem_cache_per_node;
+ long kmem_cache_per_node_ptrs_node;
};
struct size_table { /* stash of commonly-used sizes */
@@ -2478,6 +2480,7 @@ struct size_table { /* stash of commonly-used sizes */
long page_compound_order;
long folio__folio_order;
long folio__flags_1;
+ long kmem_cache_per_node_ptrs;
};
struct array_table {
diff --git a/memory.c b/memory.c
index 7102e951f1d5..7c3ab506217a 100644
--- a/memory.c
+++ b/memory.c
@@ -871,6 +871,8 @@ 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");
+ if (INVALID_MEMBER(kmem_cache_node))
+ MEMBER_OFFSET_INIT(kmem_cache_per_node, "kmem_cache",
"per_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");
@@ -922,7 +924,12 @@ vm_init(void)
if (INVALID_MEMBER(page_objects))
ANON_MEMBER_OFFSET_INIT(page_objects, "slab", "objects");
}
- if (VALID_MEMBER(kmem_cache_node)) {
+ if (VALID_MEMBER(kmem_cache_per_node)) { /* Linux 7.1 and later */
+ MEMBER_OFFSET_INIT(kmem_cache_per_node_ptrs_node,
+ "kmem_cache_per_node_ptrs", "node");
+ STRUCT_SIZE_INIT(kmem_cache_per_node_ptrs, "kmem_cache_per_node_ptrs");
+ vt->flags |= CONFIG_NUMA;
+ } else if (VALID_MEMBER(kmem_cache_node)) {
ARRAY_LENGTH_INIT(len, NULL, "kmem_cache.node", NULL, 0);
vt->flags |= CONFIG_NUMA;
}
@@ -19555,9 +19562,13 @@ 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));
+ if (VALID_MEMBER(kmem_cache_per_node)) /* Linux 7.1 and later */
+ node_ptr = ULONG(si->cache_buf + OFFSET(kmem_cache_per_node) +
+ (SIZE(kmem_cache_per_node_ptrs) * nt->node_id) +
+ OFFSET(kmem_cache_per_node_ptrs_node));
+ else
+ node_ptr = ULONG(si->cache_buf + OFFSET(kmem_cache_node) +
+ (sizeof(void *) * nt->node_id));
} else
node_ptr = si->cache +
OFFSET(kmem_cache_local_node);
diff --git a/symbols.c b/symbols.c
index 2071bdf77819..ae7fa7b416a4 100644
--- a/symbols.c
+++ b/symbols.c
@@ -10932,6 +10932,9 @@ dump_offset_table(char *spec, ulong makestruct)
OFFSET(kmem_cache_oo));
fprintf(fp, " kmem_cache_random: %ld\n",
OFFSET(kmem_cache_random));
+ fprintf(fp, " kmem_cache_per_node: %ld\n",
OFFSET(kmem_cache_per_node));
+
+ fprintf(fp, " kmem_cache_per_node_ptrs_node: %ld\n",
OFFSET(kmem_cache_per_node_ptrs_node));
fprintf(fp, " kmem_cache_node_nr_partial: %ld\n",
OFFSET(kmem_cache_node_nr_partial));
@@ -12043,6 +12046,7 @@ dump_offset_table(char *spec, ulong makestruct)
fprintf(fp, " kmem_cache: %ld\n",
SIZE(kmem_cache));
fprintf(fp, " kmem_cache_node: %ld\n",
SIZE(kmem_cache_node));
fprintf(fp, " kmem_cache_cpu: %ld\n",
SIZE(kmem_cache_cpu));
+ fprintf(fp, " kmem_cache_per_node_ptrs: %ld\n",
SIZE(kmem_cache_per_node_ptrs));
fprintf(fp, " swap_info_struct: %ld\n",
SIZE(swap_info_struct));
--
2.31.1
4
days inactive
5
days old
devel@lists.crash-utility.osci.io
1 comments
1 participants
participants (1)
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HAGIO KAZUHITO(萩尾 一仁)