[Crash-utility] Re: [PATCH] kmem: fix the determination for slab page

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&gt; 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 +#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) +{ + 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)) -- 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