[Crash-utility] Re: [PATCH 2/2] Fix "kmem [-s]" command on Linux 7.1 and later

Hi Kazu, While testing crash with recent mainline kernel, I applied your two patches. It does emit the errors mentioned, but crash failed to start, it failed in the task init path, I suspect below log with "crash -d 8": read_diskdump: paddr/pfn: 7b39d4c0/7b39d -> physical page is cached: 7b39d000 <read_diskdump: addr: ffff88807b39e000 paddr: 7b39e000 cnt: 192> read_diskdump: paddr/pfn: 7b39e000/7b39e -> physical page is cached: 7b39e000 task 1 0x8df932 please wait... (gathering task table data)<readmem: ffffffff81c25948, KVADDR, "xarray xa_head", 8, (FOE), 7ffcd7a168d0> <read_diskdump: addr: ffffffff81c25948 paddr: 2225948 cnt: 8> read_diskdump: paddr/pfn: 2225948/2225 -> cache physical page: 2225000 <readmem: ffff888003241b60, KVADDR, "xa_node shift", 1, (FOE), 7ffcd7a168cf> <read_diskdump: addr: ffff888003241b60 paddr: 3241b60 cnt: 1> read_diskdump: PAGE_EXCLUDED: paddr/pfn: 3241b60/3241 crash: page excluded: kernel virtual address: ffff888003241b60 type: "xa_node shift" And then I tried 6.19.0 kernel, crash works fine. Bisect finished with below result: bash-5.3$ git bisect bad Bisecting: 1 revision left to test after this (roughly 1 step) [d50569612c29215c5d1c64f47a65604ed265d2e9] mm: rename the 'compound_head' field in the 'struct page' to 'compound_info' bash-5.3$ git bisect view --oneline 8c846c879e22 mm: rework compound_head() for power-of-2 sizeof(struct page) 2969b42c8f99 LoongArch/mm: align vmemmap to maximal folio size 476849b0fba4 riscv/mm: align vmemmap to maximal folio size 67c79a5af051 mm: move set/clear_compound_head() next to compound_head() d50569612c29 (HEAD) mm: rename the 'compound_head' field in the 'struct page' to 'compound_info' bash-5.3$ git bisect skip There are only 'skip'ped commits left to test. The first bad commit could be any of: 476849b0fba4450f5adf22196bcff9c24c673bc4 67c79a5af051f57339ecf383d3f67e200741ce20 2969b42c8f994330fc020ec0d235aeb43bce317c d50569612c29215c5d1c64f47a65604ed265d2e9 8c846c879e226c312c2c7a7bc1e323779903530f We cannot bisect more! Bisect skipped a few commits due to kernel can not compile, but the issue seems related to those commits. Any thoughts? I suspect your fixes are not enough? Attached the kernel config, it is a very small config I tuned for testing with a kvm guest. If you need more info just let me know. On 8/2/26 1:15 PM, Dave Young wrote: > Add Kairui and Baoquan who could help to review the patch > > On 7/24/26 9:27 AM, HAGIO KAZUHITO(萩尾 一仁) wrote: >> From: Kazuhito Hagio <k-hagio-ab(a)nec.com&gt; >> >> 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&gt; >> --- >> 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)); > -- > Crash-utility mailing list -- devel(a)lists.crash-utility.osci.io > To unsubscribe send an email to devel-leave(a)lists.crash-utility.osci.io > https://${domain_name}/admin/lists/devel.lists.crash-utility.osci.io/ > Contribution Guidelines: https://github.com/crash-utility/crash/wiki > > -- > Crash-utility mailing list -- devel(a)lists.crash-utility.osci.io > To unsubscribe send an email to devel-leave(a)lists.crash-utility.osci.io > https://${domain_name}/admin/lists/devel.lists.crash-utility.osci.io/ > Contribution Guidelines: https://github.com/crash-utility/crash/wiki