Re: [PATCH] Fix for the "kmem -i" option on Linux 5.0

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----- Original Message -----
> Fix for the "kmem -i" option on Linux 5.0 and later kernels that
> contain commit ca79b0c211af63fa3276f0e3fd7dd9ada2439839, titled
> "mm: convert totalram_pages and totalhigh_pages variables to atomic".
> Without the patch, the command prints some incorrect values, and
> besides doesn't print high/low memory information on kernels which
> are configured with CONFIG_HIGHMEM.

Hi Kazu,

Thanks again -- the patch is queued for crash-7.2.6:

  https://github.com/crash-utility/crash/commit/942d813cda354a5f4234fd36e9c6734140e3ffcb

Dave


> crash> kmem -i
>                  PAGES        TOTAL      PERCENTAGE
>     TOTAL MEM  -4395174638254716088  53602483503169.4 GB         ----
>          FREE   398314       1.5 GB    0% of TOTAL MEM
>          USED  -4395174638255114402  53602483503167.9 GB    0% of TOTAL MEM
> ...
> 
> Tested with 5.0 and 4.20 Fedora kernels for x86_64 and x86.
> 
> Signed-off-by: Kazuhito Hagio <k-hagio@xxxxxxxxxxxxx>
> ---
>  memory.c | 75 +++++++++++++++++++++++++++-----------------------------
>  1 file changed, 36 insertions(+), 39 deletions(-)
> 
> diff --git a/memory.c b/memory.c
> index 9c1019a..ab561b3 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -910,26 +910,40 @@ vm_init(void)
>  	if (IS_VMALLOC_ADDR(vt->mem_map))
>  		vt->flags |= V_MEM_MAP;
>  	vt->total_pages = BTOP(VTOP(vt->high_memory));
> -	switch (get_syment_array("totalram_pages", sp_array, 2))
> -	{
> -	case 1:
> -		get_symbol_data("totalram_pages", sizeof(ulong),
> -			&vt->totalram_pages);
> -		break;
> -	case 2:
> -		if (!(readmem(sp_array[0]->value, KVADDR,
> -		    &value1, sizeof(ulong),
> -		    "totalram_pages #1", RETURN_ON_ERROR)))
> +
> +	if (symbol_exists("_totalram_pages")) {
> +		readmem(symbol_value("_totalram_pages") +
> +			OFFSET(atomic_t_counter), KVADDR,
> +			&vt->totalram_pages, sizeof(ulong),
> +			"_totalram_pages", FAULT_ON_ERROR);
> +	} else {
> +		switch (get_syment_array("totalram_pages", sp_array, 2))
> +		{
> +		case 1:
> +			get_symbol_data("totalram_pages", sizeof(ulong),
> +				&vt->totalram_pages);
>  			break;
> -                if (!(readmem(sp_array[1]->value, KVADDR,
> -                    &value2, sizeof(ulong),
> -		    "totalram_pages #2", RETURN_ON_ERROR)))
> -                        break;
> -		vt->totalram_pages = MAX(value1, value2);
> -		break;
> +		case 2:
> +			if (!(readmem(sp_array[0]->value, KVADDR,
> +			    &value1, sizeof(ulong),
> +			    "totalram_pages #1", RETURN_ON_ERROR)))
> +				break;
> +			if (!(readmem(sp_array[1]->value, KVADDR,
> +			    &value2, sizeof(ulong),
> +			    "totalram_pages #2", RETURN_ON_ERROR)))
> +				break;
> +			vt->totalram_pages = MAX(value1, value2);
> +			break;
> +		}
>  	}
>  
> -	if (symbol_exists("totalhigh_pages")) {
> +	if (symbol_exists("_totalhigh_pages")) {
> +		readmem(symbol_value("_totalhigh_pages") +
> +			OFFSET(atomic_t_counter), KVADDR,
> +			&vt->totalhigh_pages, sizeof(ulong),
> +			"_totalhigh_pages", FAULT_ON_ERROR);
> +		vt->total_pages += vt->totalhigh_pages;
> +	} else if (symbol_exists("totalhigh_pages")) {
>  	        switch (get_syment_array("totalhigh_pages", sp_array, 2))
>  	        {
>  	        case 1:
> @@ -8169,7 +8183,6 @@ dump_kmeminfo(void)
>  	long nr_file_pages, nr_slab;
>  	ulong swapper_space_nrpages;
>  	ulong pct;
> -	ulong value1, value2;
>  	uint tmp;
>  	struct meminfo meminfo;
>  	struct gnu_request req;
> @@ -8177,7 +8190,6 @@ dump_kmeminfo(void)
>          ulong get_totalram;
>          ulong get_buffers;
>          ulong get_slabs;
> -        struct syment *sp_array[2];
>  	char buf[BUFSIZE];
>  
>  
> @@ -8210,7 +8222,8 @@ dump_kmeminfo(void)
>           *    Prior to 2.3.36, count all mem_map pages minus the reserved
>           ones.
>           *    From 2.3.36 onwards, use "totalram_pages" if set.
>  	 */
> -	if (symbol_exists("totalram_pages")) {
> +	if (symbol_exists("totalram_pages") ||
> +	    symbol_exists("_totalram_pages")) {
>  		totalram_pages = vt->totalram_pages ?
>  			vt->totalram_pages : get_totalram;
>  	} else
> @@ -8362,25 +8375,9 @@ dump_kmeminfo(void)
>  	fprintf(fp, "%13s  %7ld  %11s  %3ld%% of TOTAL MEM\n",
>  		"SLAB", get_slabs, pages_to_size(get_slabs, buf), pct);
>  
> -        if (symbol_exists("totalhigh_pages")) {
> -	        switch (get_syment_array("totalhigh_pages", sp_array, 2))
> -	        {
> -	        case 1:
> -	                get_symbol_data("totalhigh_pages", sizeof(ulong),
> -	                        &totalhigh_pages);
> -	                break;
> -	        case 2:
> -	                if (!(readmem(sp_array[0]->value, KVADDR,
> -	                    &value1, sizeof(ulong),
> -	                    "totalhigh_pages #1", RETURN_ON_ERROR)))
> -	                        break;
> -	                if (!(readmem(sp_array[1]->value, KVADDR,
> -	                    &value2, sizeof(ulong),
> -	                    "totalhigh_pages #2", RETURN_ON_ERROR)))
> -	                        break;
> -	                totalhigh_pages = MAX(value1, value2);
> -	                break;
> -	        }
> +	if (symbol_exists("totalhigh_pages") ||
> +	    symbol_exists("_totalhigh_pages")) {
> +		totalhigh_pages = vt->totalhigh_pages;
>  
>  		pct = totalhigh_pages ?
>  			(totalhigh_pages * 100)/totalram_pages : 0;
> --
> 2.17.0
> 
> --
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> 

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