Hi qiwu,
Thanks for the fix, however there are several issues:
On Mon, Sep 2, 2024 at 2:30 AM <qiwu.chen@xxxxxxxxxxxxx> wrote:
>
> Hi crash maintainers,
> The previous patch is a mistake that can be ignored. Please help review the following rework patch, thanks!
>
> 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 | 73 ++++++++++++++++++++++++++++++++++++++++++++++++--------
> 2 files changed, 70 insertions(+), 10 deletions(-)
>
> diff --git a/defs.h b/defs.h
> index dfbd241..d6cb2af 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -1416,6 +1416,7 @@ struct offset_table { /* stash of commonly-used offsets */
> long page_buffers;
> long page_lru;
> long page_pte;
> + long page_page_type;
> long swap_info_struct_swap_file;
> long swap_info_struct_swap_vfsmnt;
> long swap_info_struct_flags;
The new members for the offset_table should always be appended to the
end of the struct.
> @@ -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;
> };
>
> #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 a74ebaf..f4905a2 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -323,6 +323,7 @@ static ulong kmem_cache_nodelists(ulong);
> static void dump_hstates(void);
> static ulong freelist_ptr(struct meminfo *, ulong, ulong);
> static ulong handle_each_vm_area(struct handle_each_vm_area_args *);
> +static void page_type_init(void);
>
> /*
> * Memory display modes specific to this file.
> @@ -504,6 +505,8 @@ 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"))
> + MEMBER_OFFSET_INIT(page_page_type, "page", "page_type");
>
> MEMBER_OFFSET_INIT(mm_struct_pgd, "mm_struct", "pgd");
>
> @@ -1278,6 +1281,8 @@ vm_init(void)
>
> page_flags_init();
>
> + page_type_init();
> +
> rss_page_types_init();
>
> vt->flags |= VM_INIT;
> @@ -5645,6 +5650,36 @@ PG_slab_flag_init(void)
>
> #define PGMM_CACHED (512)
>
> +#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)
> +{
> + /*
> + * The page type macros covert into enum since kernel commit ff202303c398e,
> + * use the default macro value if the vmcoreinfo without enum pagetype.
> + */
> + 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 PageSlab(ulong flags, uint page_type)
> +{
> + if (vt->flags & SLAB_PAGEFLAGS) {
> + if ((flags >> vt->PG_slab) & 1)
> + return TRUE;
> + } else if (PageType(page_type, (uint)vt->PG_slab))
> + return TRUE;
> + else
> + return FALSE;
> +}
1. The function naming better be page_slab() instead of PageSlab.
2. For the 1st "if", the page_type is not used, only used in the
"else" branch. But page_type will always be readmem() previously, also
page_type may not exist for older kernels. Can you rewrite the
function?
> +
> static void
> dump_mem_map_SPARSEMEM(struct meminfo *mi)
> {
> @@ -5657,7 +5692,7 @@ dump_mem_map_SPARSEMEM(struct meminfo *mi)
> ulong PG_reserved_flag;
> long buffers;
> ulong inode, offset, flags, mapping, index;
> - uint count;
> + uint count, page_type;
> int print_hdr, pg_spec, phys_spec, done;
> int v22;
> char hdr[BUFSIZE];
> @@ -5904,6 +5939,7 @@ dump_mem_map_SPARSEMEM(struct meminfo *mi)
> if (SIZE(page_flags) == 4)
> flags &= 0xffffffff;
> count = UINT(pcache + OFFSET(page_count));
> + page_type = UINT(pcache + OFFSET(page_page_type));
>
> switch (mi->flags)
> {
> @@ -5931,7 +5967,7 @@ 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 (PageSlab(flags, page_type))
> slabs++;
> } else {
> if ((flags >> v24_PG_slab) & 1)
> @@ -6142,7 +6178,7 @@ dump_mem_map(struct meminfo *mi)
> long buffers;
> ulong inode, offset, flags, mapping, index;
> ulong node_size;
> - uint count;
> + uint count, page_type;
> int print_hdr, pg_spec, phys_spec, done;
> int v22;
> struct node_table *nt;
> @@ -6354,6 +6390,7 @@ dump_mem_map(struct meminfo *mi)
> if (SIZE(page_flags) == 4)
> flags &= 0xffffffff;
> count = UINT(pcache + OFFSET(page_count));
> + page_type = UINT(pcache + OFFSET(page_page_type));
>
> switch (mi->flags)
> {
> @@ -6381,7 +6418,7 @@ 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 (PageSlab(flags, page_type))
> slabs++;
> } else {
> if ((flags >> v24_PG_slab) & 1)
> @@ -6694,7 +6731,6 @@ dump_hstates()
> FREEBUF(hstate);
> }
>
> -
> static void
> page_flags_init(void)
> {
> @@ -6775,6 +6811,9 @@ 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,
> @@ -6835,8 +6874,9 @@ 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]);
> -
> + vt->pageflags_data[p].mask = 1 << atoi(arglist[2]);
> + if (!strcmp(nameptr, "slab"))
> + vt->flags |= SLAB_PAGEFLAGS;
> p++;
> }
> } else
> @@ -9715,6 +9755,7 @@ vaddr_to_kmem_cache(ulong vaddr, char *buf, int verbose)
> {
> physaddr_t paddr;
> ulong page, cache, page_flags;
> + uint page_type;
>
> if (!kvtop(NULL, vaddr, &paddr, 0)) {
> if (verbose)
> @@ -9736,14 +9777,20 @@ 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))) {
> + readmem(page+OFFSET(page_page_type), KVADDR,
> + &page_type, sizeof(page_type), "page_type",
> + FAULT_ON_ERROR);
There is a problem for readmem(page_page_type), the page_type member
of struct page is not introduced for kernels such as v4.17 and prior.
E.g for 3.10:
crash> kmem -s ffff880169b30000
kmem: invalid structure member offset: page_page_type
FILE: memory.c LINE: 9780 FUNCTION: vaddr_to_kmem_cache()
[/root/crash-dev/crash] error trace: 530063 => 55e269 => 53f5d8 => 63740e
63740e: OFFSET_verify+164
53f5d8: vaddr_to_kmem_cache+299
55e269: dump_kmem_cache_slub+688
530063: cmd_kmem+3017
kmem: invalid structure member offset: page_page_type
FILE: memory.c LINE: 9780 FUNCTION: vaddr_to_kmem_cache()
Also see the comment for function PageSlab.
Thanks,
Tao Liu
> + if (!PageSlab(page_flags, page_type)) {
> 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)))
> + readmem(compound_head(page)+OFFSET(page_page_type), KVADDR,
> + &page_type, sizeof(page_type), "page_type",
> + FAULT_ON_ERROR);
> + if (!PageSlab(page_flags, page_type))
> return NULL;
> } else
> return NULL;
> @@ -20195,6 +20242,7 @@ is_slab_page(struct meminfo *si, char *buf)
> {
> int i, cnt;
> ulong page_slab, page_flags, name;
> + uint page_type;
> ulong *cache_list;
> char *retval;
>
> @@ -20209,7 +20257,12 @@ is_slab_page(struct meminfo *si, char *buf)
> RETURN_ON_ERROR|QUIET))
> return NULL;
>
> - if (!(page_flags & (1 << vt->PG_slab)))
> + if (!readmem(si->spec_addr + OFFSET(page_page_type), KVADDR,
> + &page_type, sizeof(ulong), "page.page_type",
> + RETURN_ON_ERROR|QUIET))
> + return NULL;
> +
> + if (!PageSlab(page_flags, page_type))
> return NULL;
>
> if (!readmem(si->spec_addr + OFFSET(page_slab), KVADDR,
> --
> 2.25.1
> --
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