Thank you for the comment, Kazu.
On Mon, Dec 26, 2022 at 1:29 PM HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab@xxxxxxx> wrote:
On 2022/12/23 19:42, Lianbo Jiang wrote:
> Kernel commit d42f3245c7e2 ("mm: memcg: convert vmstat slab counters to
> bytes"), which is contained in linux v5.9-rc1 and later kernels, renamed
> NR_SLAB_{RECLAIMABLE,UNRECLAIMABLE} to NR_SLAB_{RECLAIMABLE,UNRECLAIMABLE}_B.
>
> Without the patch, "kmem -i" command will display incorrect SLAB
> statistics:
>
> crash> kmem -i | grep -e PAGES -e SLAB
> PAGES TOTAL PERCENTAGE
> SLAB 89458 349.4 MB 0% of TOTAL MEM
> ^^^^^ ^^^^^
>
> With the patch, the actual result is:
> crash> kmem -i | grep -e PAGES -e SLAB
> PAGES TOTAL PERCENTAGE
> SLAB 261953 1023.3 MB 0% of TOTAL MEM
Good catch! This kind of no error issue is hard to detect..
>
> Reported-by: Buland Kumar Singh <bsingh@xxxxxxxxxx>
> Signed-off-by: Lianbo Jiang <lijiang@xxxxxxxxxx>
> ---
> memory.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/memory.c b/memory.c
> index 9d003713534b..a8f08f1a4d09 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -8382,9 +8382,11 @@ dump_kmeminfo(void)
> if (vm_stat_init()) {
> if (dump_vm_stat("NR_SLAB", &nr_slab, 0))
> get_slabs = nr_slab;
> - else if (dump_vm_stat("NR_SLAB_RECLAIMABLE", &nr_slab, 0)) {
> + else if (dump_vm_stat("NR_SLAB_RECLAIMABLE", &nr_slab, 0) ||
> + dump_vm_stat("NR_SLAB_RECLAIMABLE_B", &nr_slab, 0)) {
> get_slabs = nr_slab;
> - if (dump_vm_stat("NR_SLAB_UNRECLAIMABLE", &nr_slab, 0))
> + if (dump_vm_stat("NR_SLAB_UNRECLAIMABLE", &nr_slab, 0) ||
> + dump_vm_stat("NR_SLAB_UNRECLAIMABLE_B", &nr_slab, 0))
> get_slabs += nr_slab;
> }
> }
Isn't this better? If no NR_SLAB_RECLAIMABLE, there is no need to
search for NR_SLAB_UNRECLAIMABLE.
Originally, I had the same idea as you. But later, I noticed that there was too much duplication of code. So, eventually I used the current fix.
But anyway, if you would prefer the following change, It's also good to me.
Thanks
Lianbo
--- a/memory.c
+++ b/memory.c
@@ -8457,6 +8457,11 @@ dump_kmeminfo(void)
get_slabs = nr_slab;
if (dump_vm_stat("NR_SLAB_UNRECLAIMABLE", &nr_slab, 0))
get_slabs += nr_slab;
+ } else if (dump_vm_stat("NR_SLAB_RECLAIMABLE_B", &nr_slab, 0)) {
+ /* 5.9 and later */
+ get_slabs = nr_slab;
+ if (dump_vm_stat("NR_SLAB_UNRECLAIMABLE_B", &nr_slab, 0))
+ get_slabs += nr_slab;
}
}
Thanks,
Kazu
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