[Crash-utility] Re: [PATCH 2/4] add folio_order function

> index 60cf56a..fdea94f 100644 > --- a/defs.h > +++ b/defs.h > @@ -1425,6 +1425,7 @@ struct offset_table { /* stash of commonly-used offsets */ > long page_buffers; > long page_lru; > long page_pte; > + long folio__flags_1; New members of offset_table and size_table should always be appended to the end of the struct, not inserted in the middle. See https://github.com/crash-utility/crash/wiki "If you add struct members to tables" section.

> long swap_info_struct_swap_file; > long swap_info_struct_swap_vfsmnt; > long swap_info_struct_flags; > @@ -2398,6 +2399,7 @@ struct size_table { /* stash of commonly-used sizes */ > long probe; > long kobj_map; > long page_flags; > + long folio__flags_1; > long module_sect_attr; > long task_struct_utime; > long task_struct_stime; > @@ -6007,6 +6009,8 @@ ulong do_xarray(ulong, int, struct list_pair *, int); > #define XARRAY_TAG_MASK (3UL) > #define XARRAY_TAG_INTERNAL (2UL) > > +int folio_order(ulong folio); > + > int file_dump(ulong, ulong, ulong, int, int); > #define DUMP_FULL_NAME 0x1 > #define DUMP_INODE_ONLY 0x2 > diff --git a/memory.c b/memory.c > index cbc8d2f..9080332 100644 > --- a/memory.c > +++ b/memory.c > @@ -547,6 +547,9 @@ vm_init(void) > MEMBER_OFFSET_INIT(page_freelist, "page", "freelist"); > MEMBER_OFFSET_INIT(page_page_type, "page", "page_type"); > > + MEMBER_OFFSET_INIT(folio__flags_1, "folio", "_flags_1"); > + MEMBER_SIZE_INIT(folio__flags_1, "folio", "_flags_1"); > + > MEMBER_OFFSET_INIT(mm_struct_pgd, "mm_struct", "pgd"); > > MEMBER_OFFSET_INIT(swap_info_struct_swap_file, > @@ -5690,6 +5693,7 @@ PG_slab_flag_init(void) > > #define v26_PG_private 12 > > +#define PG_head 6 > #define PGMM_CACHED (512) > > static void > @@ -20423,6 +20427,24 @@ static unsigned int oo_objects(ulong oo) > return (oo & ((1 << 16) - 1)); > } > > +int > +folio_order(ulong folio) > +{ > + ulong v = 0; > + > + /* 1.) Check PG_head bit in the first page's flags. */ > + readmem(folio + OFFSET(page_flags), KVADDR, &v, sizeof(ulong), > + "folio.page.flags", FAULT_ON_ERROR); > + if (!(v & (1 << PG_head))) > + return 0; > + > + /* 2.) Get folio->_flags_1 in the second page */ > + readmem(folio + OFFSET(folio__flags_1), KVADDR, &v, sizeof(ulong), > + "folio->_flags_1", FAULT_ON_ERROR); > + > + return v & 0xff; > +} I encountered some regressions for this patch. See this backtrace logs: 1) #0 folio_order (folio=18446617889843220480) at memory.c:20433 #1 0x0000000000a1243b in do_xarray_count (node=18446617889843768752, slot=18446617889843220480, path=0x7fffffffbbd0 "root/0/0", index=1, private=0x7fffffffceb0) at filesys.c:4275 #2 0x00000000009be0fd in do_xarray_iter (node=18446617889843768752, height=1, path=0x7fffffffbbd0 "root/0/0", index=0, ops=0x7fffffffce90) at tools.c:4767 #3 0x00000000009be19c in do_xarray_iter (node=18446617890154567376, height=2, path=0x7fffffffc220 "root/0", index=0, ops=0x7fffffffce90) at tools.c:4774 #4 0x00000000009be19c in do_xarray_iter (node=18446617886337392040, height=3, path=0x7fffffffc860 "root", index=0, ops=0x7fffffffce90) at tools.c:4774 #5 0x00000000009be5ca in do_xarray_traverse (ptr=18446744071941975336, is_root=1, ops=0x7fffffffce90) at tools.c:4849 #6 0x0000000000a127d3 in do_xarray (root=18446744071941975336, flag=1, xp=0x0, type=0) at filesys.c:4409 #7 0x0000000000a1c7d9 in refresh_xarray_task_table () at task.c:2613 #8 0x0000000000a16c07 in task_init () at task.c:670 #9 0x00000000009aa445 in main_loop () at main.c:799 #10 0x0000000000807add in captured_main (data=<optimized out>) at main.c:1374 #11 gdb_main (args=<optimized out>) at main.c:1407 #12 0x0000000000807b45 in gdb_main_entry (argc=2, argv=0x7fffffffd908) at main.c:1434 #13 0x0000000000a61d0b in gdb_main_loop (argc=2, argv=0x7fffffffd908) at gdb_interface.c:81 #14 0x00000000009aa290 in main (argc=3, argv=0x7fffffffd908) at main.c:732 (gdb) p offset_table.page_flags $1 = 0 (gdb) p offset_table.folio__flags_1 $2 = -1 20438 if (!(v & (1 << PG_head))) (gdb) p v $3 = 112 crash: invalid structure member offset: folio__flags_1 FILE: memory.c LINE: 20442 FUNCTION: folio_order() Kernel version: 4.20.0-0.rc3, also I see plenty of similar regressions for kernels 4.18, 5.2 ... 2) Also emerge some warnings: bpf: invalid kernel virtual address: 0 type: "folio.page.flags" #0 readmem (addr=0, memtype=1, buffer=0x7fffffff9998, size=8, type=0xda350f "folio.page.flags", error_handle=1) at memory.c:2411 #1 0x0000000000a0595a in folio_order (folio=0) at memory.c:20436 #2 0x0000000000a1243b in do_xarray_count (node=0, slot=0, path=0x7fffffff9a20 "direct", index=0, private=0x7fffffffa070) at filesys.c:4275 #3 0x00000000009be592 in do_xarray_traverse (ptr=18446744072013761824, is_root=1, ops=0x7fffffffa050) at tools.c:4846 #4 0x0000000000a127d3 in do_xarray (root=18446744072013761824, flag=1, xp=0x0, type=0) at filesys.c:4409 #5 0x0000000000a7512b in bpf_init (bpf=0x12b3e80 <bpf_info>) at bpf.c:346 #6 0x0000000000a7568f in do_bpf (flags=0, prog_id=0, map_id=0, radix=0) at bpf.c:438 #7 0x0000000000a747ea in cmd_bpf () at bpf.c:215 #8 0x00000000009aa7e1 in exec_command () at main.c:904 #9 0x00000000009aa5d3 in main_loop () at main.c:851 #10 0x0000000000807add in captured_main (data=<optimized out>) at main.c:1374 #11 gdb_main (args=<optimized out>) at main.c:1407 #12 0x0000000000807b45 in gdb_main_entry (argc=2, argv=0x7fffffffd918) at main.c:1434 #13 0x0000000000a61d0b in gdb_main_loop (argc=2, argv=0x7fffffffd918) at gdb_interface.c:81 #14 0x00000000009aa290 in main (argc=3, argv=0x7fffffffd918) at main.c:732 Could you please check for those?