Thank you for the update, Qiwu.
On Wed, Sep 11, 2024 at 10:27 AM <devel-request@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Date: Wed, 11 Sep 2024 02:25:40 -0000
From: qiwu.chen@xxxxxxxxxxxxx
Subject: [Crash-utility] [PATCH v2] kmem: fix the determination for
slab page
To: devel@xxxxxxxxxxxxxxxxxxxxxxxxxxx
Message-ID: <20240911022540.15869.84683@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
Content-Type: text/plain; charset="utf-8"
The determination for a slab page has changed due to changing
PG_slab from a page flag to a page type since kernel commit
46df8e73a4a3.
Before apply this patch:
crash> kmem -s ffff000002aa4100
kmem: address is not allocated in slab subsystem: ffff000002aa4100
After apply this patch:
crash> kmem -s ffff000002aa4100
CACHE OBJSIZE ALLOCATED TOTAL SLABS SSIZE NAME
ffff00000140f900 4096 94 126 18 32k task_struct
SLAB MEMORY NODE TOTAL ALLOCATED FREE
fffffdffc00aa800 ffff000002aa0000 0 7 5 2
FREE / [ALLOCATED]
[ffff000002aa4100]
Signed-off-by: qiwu.chen <qiwu.chen@xxxxxxxxxxxxx>
---
defs.h | 7 ++++++
memory.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++---------
2 files changed, 62 insertions(+), 10 deletions(-)
diff --git a/defs.h b/defs.h
index 2231cb6..e2a9278 100644
--- a/defs.h
+++ b/defs.h
@@ -2243,6 +2243,7 @@ struct offset_table { /* stash of commonly-used offsets */
long vmap_node_busy;
long rb_list_head;
long file_f_inode;
+ long page_page_type;
};
struct size_table { /* stash of commonly-used sizes */
@@ -2651,6 +2652,7 @@ struct vm_table { /* kernel VM-related data */
ulong max_mem_section_nr;
ulong zero_paddr;
ulong huge_zero_paddr;
+ uint page_type_base;
};
Can you try to dump the values of the above two variables from the dump_vm_table() and dump_offset_table()? We can display their values by help -v and help -o options.
#define NODES (0x1)
@@ -2684,6 +2686,11 @@ struct vm_table { /* kernel VM-related data */
#define SLAB_CPU_CACHE (0x10000000)
#define SLAB_ROOT_CACHES (0x20000000)
#define USE_VMAP_NODES (0x40000000)
+/*
+ * The SLAB_PAGEFLAGS flag is introduced to detect the change of
+ * PG_slab's type from a page flag to a page type.
+ */
+#define SLAB_PAGEFLAGS (0x80000000)
#define IS_FLATMEM() (vt->flags & FLATMEM)
#define IS_DISCONTIGMEM() (vt->flags & DISCONTIGMEM)
diff --git a/memory.c b/memory.c
index 967a9cf..48ac627 100644
--- a/memory.c
+++ b/memory.c
@@ -351,6 +351,43 @@ static ulong handle_each_vm_area(struct handle_each_vm_area_args *);
static ulong DISPLAY_DEFAULT;
+/*
+ * Before kernel commit ff202303c398e, the value is defined as a macro, so copy it here;
+ * After this commit, the value is defined as an enum, which can be evaluated at runtime.
+ */
+#define PAGE_TYPE_BASE 0xf0000000
+#define PageType(page_type, flag) \
+ ((page_type & (vt->page_type_base | flag)) == vt->page_type_base)
+
+static void page_type_init(void)
+{
+ if (!enumerator_value("PAGE_TYPE_BASE", (long *)&vt->page_type_base))
+ vt->page_type_base = PAGE_TYPE_BASE;
+}
+
+/*
+ * The PG_slab's type has changed from a page flag to a page type
+ * since kernel commit 46df8e73a4a3.
+ */
+static bool page_slab(ulong page, ulong flags)
+{
+ if (vt->flags & SLAB_PAGEFLAGS) {
+ if ((flags >> vt->PG_slab) & 1)
+ return TRUE;
+ }
+
+ if (VALID_MEMBER(page_page_type)) {
+ uint page_type;
+
+ readmem(page+OFFSET(page_page_type), KVADDR, &page_type,
+ sizeof(page_type), "page_type", FAULT_ON_ERROR);
+ if (PageType(page_type, (uint)vt->PG_slab))
+ return TRUE;
+ }
+
+ return FALSE;
+}
+
/*
* Verify that the sizeof the primitive types are reasonable.
*/
@@ -504,6 +541,10 @@ vm_init(void)
ANON_MEMBER_OFFSET_INIT(page_compound_head, "page", "compound_head");
MEMBER_OFFSET_INIT(page_private, "page", "private");
MEMBER_OFFSET_INIT(page_freelist, "page", "freelist");
+ if (MEMBER_EXISTS("page", "page_type")) {
When initializing the page_page_type, the above "if" check seems to be redundant.
+ MEMBER_OFFSET_INIT(page_page_type, "page", "page_type");
+ page_type_init();
Can this page_type_init() be moved to the page_flags_init()?
Other changes are fine to me.
Thanks
Lianbo
+ }
MEMBER_OFFSET_INIT(mm_struct_pgd, "mm_struct", "pgd");
@@ -5931,7 +5972,7 @@ dump_mem_map_SPARSEMEM(struct meminfo *mi)
if ((flags >> v22_PG_Slab) & 1)
slabs++;
} else if (vt->PG_slab) {
- if ((flags >> vt->PG_slab) & 1)
+ if (page_slab(pp, flags))
slabs++;
} else {
if ((flags >> v24_PG_slab) & 1)
@@ -6381,7 +6422,7 @@ dump_mem_map(struct meminfo *mi)
if ((flags >> v22_PG_Slab) & 1)
slabs++;
} else if (vt->PG_slab) {
- if ((flags >> vt->PG_slab) & 1)
+ if (page_slab(pp, flags))
slabs++;
} else {
if ((flags >> v24_PG_slab) & 1)
@@ -6775,6 +6816,9 @@ page_flags_init_from_pageflag_names(void)
vt->pageflags_data[i].name = nameptr;
vt->pageflags_data[i].mask = mask;
+ if (!strncmp(nameptr, "slab", 4))
+ vt->flags |= SLAB_PAGEFLAGS;
+
if (CRASHDEBUG(1)) {
fprintf(fp, " %08lx %s\n",
vt->pageflags_data[i].mask,
@@ -6836,7 +6880,8 @@ page_flags_init_from_pageflags_enum(void)
strcpy(nameptr, arglist[0] + strlen("PG_"));
vt->pageflags_data[p].name = nameptr;
vt->pageflags_data[p].mask = 1 << atoi(arglist[2]);
-
+ if (!strncmp(nameptr, "slab", 4))
+ vt->flags |= SLAB_PAGEFLAGS;
p++;
}
} else
@@ -9736,14 +9781,14 @@ vaddr_to_kmem_cache(ulong vaddr, char *buf, int verbose)
readmem(page+OFFSET(page_flags), KVADDR,
&page_flags, sizeof(ulong), "page.flags",
FAULT_ON_ERROR);
- if (!(page_flags & (1 << vt->PG_slab))) {
+ if (!page_slab(page, page_flags)) {
if (((vt->flags & KMALLOC_SLUB) || VALID_MEMBER(page_compound_head)) ||
((vt->flags & KMALLOC_COMMON) &&
VALID_MEMBER(page_slab) && VALID_MEMBER(page_first_page))) {
readmem(compound_head(page)+OFFSET(page_flags), KVADDR,
&page_flags, sizeof(ulong), "page.flags",
FAULT_ON_ERROR);
- if (!(page_flags & (1 << vt->PG_slab)))
+ if (!page_slab(compound_head(page), page_flags))
return NULL;
} else
return NULL;
@@ -20195,7 +20240,7 @@ char *
is_slab_page(struct meminfo *si, char *buf)
{
int i, cnt;
- ulong page_slab, page_flags, name;
+ ulong pg_slab, page_flags, name;
ulong *cache_list;
char *retval;
@@ -20210,11 +20255,11 @@ is_slab_page(struct meminfo *si, char *buf)
RETURN_ON_ERROR|QUIET))
return NULL;
- if (!(page_flags & (1 << vt->PG_slab)))
+ if (!page_slab(si->spec_addr, page_flags))
return NULL;
- if (!readmem(si->spec_addr + OFFSET(page_slab), KVADDR,
- &page_slab, sizeof(ulong), "page.slab",
+ if (!readmem(si->spec_addr + OFFSET(page_slab), KVADDR,
+ &pg_slab, sizeof(ulong), "page.slab",
RETURN_ON_ERROR|QUIET))
return NULL;
@@ -20222,7 +20267,7 @@ is_slab_page(struct meminfo *si, char *buf)
cnt = get_kmem_cache_list(&cache_list);
for (i = 0; i < cnt; i++) {
- if (page_slab == cache_list[i]) {
+ if (pg_slab == cache_list[i]) {
if (!readmem(cache_list[i] + OFFSET(kmem_cache_name),
KVADDR, &name, sizeof(char *),
"kmem_cache.name", QUIET|RETURN_ON_ERROR))
--
2.25.1
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