Hi Chengen,

thank you for the update.

On 2023/11/17 12:45, Chengen Du wrote:
> A kernel commit 7ac07a26dea7 (zram: preparation for multi-zcomp support)
> in Linux replaces "compressor" with "comp_algs" in the zram struct.
> If not fixed, the issue triggers the following error:
>    rd: WARNING: Some pages are swapped out to zram. Please run mod -s zram.
>    rd: invalid user virtual address: ffff7d23f010  type: "64-bit UVADDR"
>
> Signed-off-by: Chengen Du <chengen.du@canonical.com>
> ---
>   defs.h     |  1 +
>   diskdump.c | 56 +++++++++++++++++++++++++++++++++++-------------------
>   2 files changed, 37 insertions(+), 20 deletions(-)
>
> diff --git a/defs.h b/defs.h
> index 788f63a..2cae5b6 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -2227,6 +2227,7 @@ struct offset_table {                    /* stash of commonly-used offsets */
>       long module_memory_size;
>       long irq_data_irq;
>       long zspage_huge;
> +     long zram_comp_algs;
>   };
>   
>   struct size_table {         /* stash of commonly-used sizes */
> diff --git a/diskdump.c b/diskdump.c
> index 0fe46f4..d7e4380 100644
> --- a/diskdump.c
> +++ b/diskdump.c
> @@ -2757,6 +2757,8 @@ diskdump_device_dump_info(FILE *ofp)
>   
>   static ulong ZRAM_FLAG_SHIFT;
>   static ulong ZRAM_FLAG_SAME_BIT;
> +static ulong ZRAM_COMP_PRIORITY_BIT1;
> +static ulong ZRAM_COMP_PRIORITY_MASK;
>   
>   static void
>   zram_init(void)
> @@ -2765,6 +2767,8 @@ zram_init(void)
>   
>       MEMBER_OFFSET_INIT(zram_mempoll, "zram", "mem_pool");
>       MEMBER_OFFSET_INIT(zram_compressor, "zram", "compressor");
> +     if (INVALID_MEMBER(zram_compressor))
> +             MEMBER_OFFSET_INIT(zram_comp_algs, "zram", "comp_algs");
>       MEMBER_OFFSET_INIT(zram_table_flag, "zram_table_entry", "flags");
>       if (INVALID_MEMBER(zram_table_flag))
>               MEMBER_OFFSET_INIT(zram_table_flag, "zram_table_entry", "value");
> @@ -2782,6 +2786,8 @@ zram_init(void)
>   
>       ZRAM_FLAG_SHIFT = 1 << zram_flag_shift;
>       ZRAM_FLAG_SAME_BIT = 1 << (zram_flag_shift+1);
> +     ZRAM_COMP_PRIORITY_BIT1 = ZRAM_FLAG_SHIFT + 7;
> +     ZRAM_COMP_PRIORITY_MASK = 0x3;
>   
>       if (CRASHDEBUG(1))
>               fprintf(fp, "zram_flag_shift: %ld\n", zram_flag_shift);
> @@ -2980,13 +2986,15 @@ try_zram_decompress(ulonglong pte_val, unsigned char *buf, ulong len, ulonglong
>       unsigned char *outbuf = NULL;
>       ulong zram, zram_table_entry, sector, index, entry, flags, size,
>               outsize, off;
> +     int comp_alg_unavail;
>   
> -     if (INVALID_MEMBER(zram_compressor)) {
> +     comp_alg_unavail = INVALID_MEMBER(zram_compressor) && INVALID_MEMBER(zram_comp_algs);
> +     if (comp_alg_unavail) {

This variable saves nothing, and looking around, I found that we don't
need to use the zram.comp* members.  The offset of zram.mem_pool has
been used since the first implementation [1], so I would like to change
this to INVALID_MEMBER(zram_mem_pool) and attached it.

So the patch is ok.

Acked-by: Kazuhito Hagio <k-hagio-ab@nec.com>

[1] https://github.com/crash-utility/crash/commit/b12bdd36cf7c


Lianbo, zram related offsets have some typos, irregular names and lack
of "help -o" output.  I made the patch 2/2 in this opportunity, could
you review this too?

Thanks,
Kazu