Hi qiwu,
On Tue, Sep 10, 2024 at 3:20 PM <qiwu.chen@xxxxxxxxxxxxx> wrote:
>
> Hi Tao,
> Thanks for your review.
> >
> > Thanks for the fix, however there are several issues:
> >
> > On Mon, Sep 2, 2024 at 2:30 AM <qiwu.chen(a)transsion.com> wrote:
> >
> > The new members for the offset_table should always be appended to the
> > end of the struct.
> >
> >
> > 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?
> >
> >
> > 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.
> >
> I make a improvement in the following change as your comments. The page_slab() function will resolve the problem for readmem(page_page_type), since it will test the page_type member of struct page exist before readmem(page_page_type).
>
> 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;
> };
>
> #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..a2885bd 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;
>
> +#define PAGE_TYPE_BASE 0xf0000000
Can we remove this one? I see the value has been changed into a new
one since v6.11-rc1.
PAGE_TYPE_BASE = 0x80000000
Is keeping the value hard coded here necessary?
> +#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 page_slab(ulong pp, ulong flags)
The variable name "pp" doesn't make sense. No one knows what pp is
until you read its context.
> +{
> + if (vt->flags & SLAB_PAGEFLAGS) {
> + if ((flags >> vt->PG_slab) & 1)
> + return TRUE;
> + }
> +
> + if (VALID_MEMBER(page_page_type)) {
> + uint page_type;
> +
> + readmem(pp+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")) {
> + MEMBER_OFFSET_INIT(page_page_type, "page", "page_type");
> + page_type_init();
> + }
>
> 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",
> + &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))
> --
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