5:58 p.m.
Kernel commit e36ce448a08d ("mm/slab: use kmalloc_node() for off slab
freelist_idx_t array allocation"), which is contained in Linux 6.1 and
later kernels, removed kmem_cache.freelist_cache member.
Without the patch, crash does not set SLAB_OVERLOAD_PAGE and
"kmem -s|-S" options fail with the following error:
kmem: invalid structure member offset: slab_list
FILE: memory.c LINE: 12156 FUNCTION: verify_slab_v2()
Use kmem_cache.freelist_size instead, which was instroduced together
with kmem_cache.freelist_cache by kernel commit 8456a648cf44.
Signed-off-by: Kazuhito Hagio <k-hagio-ab(a)nec.com>
---
memory.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/memory.c b/memory.c
index 625a94b7d7d4..71ded688206f 100644
--- a/memory.c
+++ b/memory.c
@@ -535,8 +535,11 @@ vm_init(void)
/*
* slab: overload struct slab over struct page
* https://lkml.org/lkml/2013/10/16/155
+ *
+ * commit e36ce448a08d removed kmem_cache.freelist_cache in 6.1,
+ * so use freelist_size instead.
*/
- if (MEMBER_EXISTS("kmem_cache", "freelist_cache")) {
+ if (MEMBER_EXISTS("kmem_cache", "freelist_size")) {
vt->flags |= SLAB_OVERLOAD_PAGE;
ANON_MEMBER_OFFSET_INIT(page_s_mem, "page", "s_mem");
ANON_MEMBER_OFFSET_INIT(page_freelist, "page", "freelist");
--
2.31.1
5:58 p.m.
New subject: [PATCH 2/2] SLAB: Fix for "kmem -s|-S" options on Linux 6.2-rc1 and later
Kernel commit 130d4df57390 ("mm/sl[au]b: rearrange struct slab fields to
allow larger rcu_head"), which is contained in Linux 6.2-rc1 and later
kernels, changed the offset of slab.slab_list and now it's not equal to
the offset of page.lru.
Without the patch, "kmem -s|-S" options print errors and zeros for slab
counters like this for kernels configured with CONFIG_SLAB=y.
crash> kmem -s
CACHE OBJSIZE ALLOCATED TOTAL SLABS SSIZE NAME
kmem: rpc_inode_cache: partial list: page/slab: fffff31ac4125190 bad active counter:
99476865
kmem: rpc_inode_cache: partial list: page/slab: fffff31ac4125190 bad s_mem pointer:
100000003
kmem: rpc_inode_cache: full list: page/slab: fffff31ac4125150 bad active counter:
99476225
kmem: rpc_inode_cache: full list: page/slab: fffff31ac4125150 bad active counter:
99476225
kmem: rpc_inode_cache: full list: page/slab: fffff31ac4125150 bad s_mem pointer:
100000005
ffff930202adfb40 704 0 0 0 4k rpc_inode_cache
...
Signed-off-by: Kazuhito Hagio <k-hagio-ab(a)nec.com>
---
memory.c | 45 +++++++++++++++++++++++++--------------------
1 file changed, 25 insertions(+), 20 deletions(-)
diff --git a/memory.c b/memory.c
index 71ded688206f..156de2f7b5a3 100644
--- a/memory.c
+++ b/memory.c
@@ -78,6 +78,7 @@ struct meminfo { /* general purpose memory information
structure */
int *freelist;
int freelist_index_size;
ulong random;
+ ulong list_offset;
};
/*
@@ -553,6 +554,8 @@ vm_init(void)
MEMBER_OFFSET_INIT(page_freelist, "slab", "freelist");
if (INVALID_MEMBER(page_active))
MEMBER_OFFSET_INIT(page_active, "slab", "active");
+
+ MEMBER_OFFSET_INIT(slab_slab_list, "slab", "slab_list");
}
if (!VALID_STRUCT(kmem_slab_s) && VALID_STRUCT(slab_s)) {
@@ -10767,6 +10770,8 @@ dump_kmem_cache_percpu_v2(struct meminfo *si)
if (vt->flags & SLAB_OVERLOAD_PAGE) {
si->freelist = si->kmem_bufctl;
si->freelist_index_size = slab_freelist_index_size();
+ si->list_offset = VALID_MEMBER(slab_slab_list) ?
+ OFFSET(slab_slab_list) : OFFSET(page_lru);
}
for (i = 0; i < vt->kmem_max_cpus; i++)
si->cpudata[i] = (ulong *)
@@ -11983,7 +11988,7 @@ do_slab_chain_slab_overload_page(long cmd, struct meminfo *si)
}
last = si->slab;
- readmem(si->slab - OFFSET(page_lru), KVADDR, page_buf,
+ readmem(si->slab - si->list_offset, KVADDR, page_buf,
SIZE(page), "page (slab) buffer",
FAULT_ON_ERROR);
@@ -11996,8 +12001,7 @@ do_slab_chain_slab_overload_page(long cmd, struct meminfo *si)
si->num_slabs++;
- si->slab = ULONG(page_buf +
- OFFSET(page_lru));
+ si->slab = ULONG(page_buf + si->list_offset);
/*
* Check for slab transition. (Tony Dziedzic)
@@ -12024,11 +12028,11 @@ do_slab_chain_slab_overload_page(long cmd, struct meminfo *si)
case SLAB_WALKTHROUGH:
if (si->flags & SLAB_OVERLOAD_PAGE_PTR) {
specified_slab = si->spec_addr;
- si->slab = si->spec_addr + OFFSET(page_lru);
+ si->slab = si->spec_addr + si->list_offset;
} else {
specified_slab = si->slab;
if (si->slab)
- si->slab += OFFSET(page_lru);
+ si->slab += si->list_offset;
}
si->flags |= (SLAB_WALKTHROUGH|SLAB_FIRST_NODE);
si->flags &= ~SLAB_GET_COUNTS;
@@ -12082,7 +12086,7 @@ do_slab_chain_slab_overload_page(long cmd, struct meminfo *si)
if (si->slab == slab_chains[s])
continue;
- readmem(si->slab - OFFSET(page_lru), KVADDR, page_buf,
+ readmem(si->slab - si->list_offset, KVADDR, page_buf,
SIZE(page), "page (slab) buffer",
FAULT_ON_ERROR);
@@ -12242,7 +12246,7 @@ verify_slab_overload_page(struct meminfo *si, ulong last, int s)
errcnt = 0;
- if (!readmem(si->slab - OFFSET(page_lru), KVADDR, page_buf,
+ if (!readmem(si->slab - si->list_offset, KVADDR, page_buf,
SIZE(page), "page (slab) buffer", QUIET|RETURN_ON_ERROR)) {
error(INFO, "%s: %s list: bad slab pointer: %lx\n",
si->curname, list, si->slab);
@@ -12250,7 +12254,7 @@ verify_slab_overload_page(struct meminfo *si, ulong last, int s)
return FALSE;
}
- list_head = (struct kernel_list_head *)(page_buf + OFFSET(page_lru));
+ list_head = (struct kernel_list_head *)(page_buf + si->list_offset);
if (!IS_KVADDR((ulong)list_head->next) ||
!accessible((ulong)list_head->next)) {
error(INFO, "%s: %s list: page/slab: %lx bad next pointer:
%lx\n",
@@ -12569,7 +12573,7 @@ dump_slab_overload_page(struct meminfo *si)
int tmp;
ulong slab_overload_page, freelist;
- slab_overload_page = si->slab - OFFSET(page_lru);
+ slab_overload_page = si->slab - si->list_offset;
readmem(slab_overload_page + OFFSET(page_s_mem),
KVADDR, &si->s_mem, sizeof(ulong),
@@ -12796,12 +12800,12 @@ gather_slab_free_list_slab_overload_page(struct meminfo *si)
if (CRASHDEBUG(1))
fprintf(fp, "slab page: %lx active: %ld si->c_num: %ld\n",
- si->slab - OFFSET(page_lru), si->s_inuse, si->c_num);
+ si->slab - si->list_offset, si->s_inuse, si->c_num);
if (si->s_inuse == si->c_num )
return;
- slab_overload_page = si->slab - OFFSET(page_lru);
+ slab_overload_page = si->slab - si->list_offset;
readmem(slab_overload_page + OFFSET(page_freelist),
KVADDR, &freelist, sizeof(void *), "page freelist",
FAULT_ON_ERROR);
@@ -13099,7 +13103,7 @@ dump_slab_objects_percpu(struct meminfo *si)
if ((si->flags & ADDRESS_SPECIFIED) &&
(vt->flags & SLAB_OVERLOAD_PAGE)) {
- readmem(si->slab - OFFSET(page_lru) + OFFSET(page_freelist),
+ readmem(si->slab - si->list_offset + OFFSET(page_freelist),
KVADDR, &freelist, sizeof(ulong), "page.freelist",
FAULT_ON_ERROR);
@@ -18713,6 +18717,9 @@ dump_kmem_cache_slub(struct meminfo *si)
si->cache_buf = GETBUF(SIZE(kmem_cache));
+ si->list_offset = VALID_MEMBER(slab_slab_list) ?
+ OFFSET(slab_slab_list) : OFFSET(page_lru);
+
if (VALID_MEMBER(page_objects) &&
OFFSET(page_objects) == OFFSET(page_inuse))
si->flags |= SLAB_BITFIELD;
@@ -19484,7 +19491,6 @@ 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;
@@ -19498,7 +19504,7 @@ 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 - list_off;
+ si->slab = last = next - si->list_offset;
if (first++ == 0)
fprintf(fp, " %s", slab_hdr);
@@ -19521,7 +19527,7 @@ do_node_lists_slub(struct meminfo *si, ulong node_ptr, int node)
if (!IS_KVADDR(next) ||
((next != list_head) &&
- !is_page_ptr(next - list_off, NULL))) {
+ !is_page_ptr(next - si->list_offset, NULL))) {
error(INFO,
"%s: partial list slab: %lx invalid page.lru.next: %lx\n",
si->curname, last, next);
@@ -19548,7 +19554,7 @@ 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 - list_off;
+ si->slab = next - si->list_offset;
if (first++ == 0)
fprintf(fp, " %s", slab_hdr);
@@ -19765,7 +19771,6 @@ 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;
@@ -19777,12 +19782,12 @@ count_partial(ulong node, struct meminfo *si, ulong *free)
hq_open();
while (next != list_head) {
- if (!readmem(next - list_off + OFFSET(page_inuse),
+ if (!readmem(next - si->list_offset + OFFSET(page_inuse),
KVADDR, &inuse, sizeof(ushort), "page.inuse", RETURN_ON_ERROR)) {
hq_close();
return -1;
}
- last = next - list_off;
+ last = next - si->list_offset;
if (inuse == -1) {
error(INFO,
@@ -19808,7 +19813,7 @@ count_partial(ulong node, struct meminfo *si, ulong *free)
}
if (!IS_KVADDR(next) ||
((next != list_head) &&
- !is_page_ptr(next - list_off, NULL))) {
+ !is_page_ptr(next - si->list_offset, NULL))) {
error(INFO, "%s: partial list slab: %lx invalid page.lru.next: %lx\n",
si->curname, last, next);
break;
--
2.31.1
8 p.m.
On Fri, Jan 6, 2023 at 7:58 AM HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab(a)nec.com>
wrote:
Kernel commit e36ce448a08d ("mm/slab: use kmalloc_node() for off
slab
freelist_idx_t array allocation"), which is contained in Linux 6.1 and
later kernels, removed kmem_cache.freelist_cache member.
Without the patch, crash does not set SLAB_OVERLOAD_PAGE and
"kmem -s|-S" options fail with the following error:
kmem: invalid structure member offset: slab_list
FILE: memory.c LINE: 12156 FUNCTION: verify_slab_v2()
Use kmem_cache.freelist_size instead, which was instroduced together
with kmem_cache.freelist_cache by kernel commit 8456a648cf44.
These two patches look good to me. For them:
[1] [PATCH 1/2] SLAB: Fix for "kmem -s|-S" options on Linux 6.1 and later
[2] [PATCH 2/2] SLAB: Fix for "kmem -s|-S" options on Linux 6.2-rc1 and
later
Ack.
Thanks.
Lianbo
Signed-off-by: Kazuhito Hagio <k-hagio-ab(a)nec.com>
---
memory.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/memory.c b/memory.c
index 625a94b7d7d4..71ded688206f 100644
--- a/memory.c
+++ b/memory.c
@@ -535,8 +535,11 @@ vm_init(void)
/*
* slab: overload struct slab over struct page
* https://lkml.org/lkml/2013/10/16/155
+ *
+ * commit e36ce448a08d removed kmem_cache.freelist_cache in 6.1,
+ * so use freelist_size instead.
*/
- if (MEMBER_EXISTS("kmem_cache", "freelist_cache")) {
+ if (MEMBER_EXISTS("kmem_cache", "freelist_size")) {
vt->flags |= SLAB_OVERLOAD_PAGE;
ANON_MEMBER_OFFSET_INIT(page_s_mem, "page",
"s_mem");
ANON_MEMBER_OFFSET_INIT(page_freelist, "page",
"freelist");
--
2.31.1
8:51 p.m.
On 2023/01/10 11:00, lijiang wrote:
On Fri, Jan 6, 2023 at 7:58 AM HAGIO KAZUHITO(萩尾 一仁)
<k-hagio-ab(a)nec.com>
wrote:
> Kernel commit e36ce448a08d ("mm/slab: use kmalloc_node() for off slab
> freelist_idx_t array allocation"), which is contained in Linux 6.1 and
> later kernels, removed kmem_cache.freelist_cache member.
>
> Without the patch, crash does not set SLAB_OVERLOAD_PAGE and
> "kmem -s|-S" options fail with the following error:
>
> kmem: invalid structure member offset: slab_list
> FILE: memory.c LINE: 12156 FUNCTION: verify_slab_v2()
>
> Use kmem_cache.freelist_size instead, which was instroduced together
> with kmem_cache.freelist_cache by kernel commit 8456a648cf44.
>
These two patches look good to me. For them:
[1] [PATCH 1/2] SLAB: Fix for "kmem -s|-S" options on Linux 6.1 and later
[2] [PATCH 2/2] SLAB: Fix for "kmem -s|-S" options on Linux 6.2-rc1 and
later
Ack.
Thank you for reviewing them, applied.
Kazu
718
days inactive
723
days old
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3 comments
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HAGIO KAZUHITO(萩尾 一仁) -
lijiang