On 2023/08/08 22:25, Lianbo Jiang wrote:
> Kernel commit eca56ff906bd ("mm, shmem: add internal shmem resident
> memory accounting"), which adds internal shmem resident memory
> accounting, and tallies into the mm_rss_stat counter.
>
> As a result, the "ps/vm" commands fail to show correct memory usage when
> a process uses an anonymous shared memory region.
>
> Without the patch:
> crash> ps 2150
> PID PPID CPU TASK ST %MEM VSZ RSS COMM
> 2150 2105 14 ffff8fba86d74d40 IN 0.0 10488392 444 mmap_test
> ^^^
Good catch! and thank you for the fix.
>
> Currently, the "ps/vm" commands missed the shmem pages count, let's
> count the shmem pages together with regular files and anonymous pages.
>
> With the patch:
> crash> ps 2150
> PID PPID CPU TASK ST %MEM VSZ RSS COMM
> 2150 2105 14 ffff8fba86d74d40 IN 20.8 10488392 3659008 mmap_test
>
> Reported-by: Buland Kumar Singh <bsingh@xxxxxxxxxx>
> Signed-off-by: Lianbo Jiang <lijiang@xxxxxxxxxx>
> ---
> defs.h | 1 +
> memory.c | 59 ++++++++++++++++++++++++++++++++++++++++++--------------
> task.c | 1 +
> 3 files changed, 46 insertions(+), 15 deletions(-)
>
> diff --git a/defs.h b/defs.h
> index 5ee60f1eb3a5..f784d40c0b17 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -887,6 +887,7 @@ struct task_table { /* kernel/local task table data */
> int callbacks;
> struct task_context **context_by_task; /* task_context sorted by task addr */
> ulong pid_xarray;
> + long shmempages;
> };
>
> #define TASK_INIT_DONE (0x1)
> diff --git a/memory.c b/memory.c
> index acbee6389472..df85b69963b6 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -4466,13 +4466,13 @@ in_user_stack(ulong task, ulong vaddr)
> }
>
> /*
> - * Set the const value of filepages and anonpages
> - * according to MM_FILEPAGES and MM_ANONPAGES.
> + * Set the const value of filepages, anonpages and shmempages
> + * according to MM_FILEPAGES, MM_ANONPAGES and MM_SHMEMPAGES.
> */
> static void
> rss_page_types_init(void)
> {
> - long anonpages, filepages;
> + long anonpages, filepages, shmempages;
>
> if (VALID_MEMBER(mm_struct_rss))
> return;
> @@ -4487,6 +4487,15 @@ rss_page_types_init(void)
> }
> tt->filepages = filepages;
> tt->anonpages = anonpages;
> +
> + /*
> + * The default value(MM_SHMEMPAGES) is 3, which is introduced
> + * in linux v4.5-rc1 and later. See commit eca56ff906bd.
> + */
> + if (!enumerator_value("MM_SHMEMPAGES", &shmempages))
> + tt->shmempages = -1;
> + else
> + tt->shmempages = shmempages;
> }
> }
>
> @@ -4812,10 +4821,11 @@ get_task_mem_usage(ulong task, struct task_mem_usage *tm)
> * Latest kernels have mm_struct.mm_rss_stat[].
> */
> if (VALID_MEMBER(mm_struct_rss_stat) && VALID_MEMBER(mm_rss_stat_count)) {
> - long anonpages, filepages, count;
> + long anonpages, filepages, shmempages, count;
>
> anonpages = tt->anonpages;
> filepages = tt->filepages;
> + shmempages = tt->shmempages;
> count = LONG(tt->mm_struct +
> OFFSET(mm_struct_rss_stat) +
> OFFSET(mm_rss_stat_count) +
> @@ -4836,6 +4846,15 @@ get_task_mem_usage(ulong task, struct task_mem_usage *tm)
> if (count > 0)
> rss += count;
>
> + if (shmempages > 0) {
This should be "shmempages >= 0"?
Fixed it at my end and applied with tweaking the commit log a bit.
https://github.com/crash-utility/crash/commit/69f38d777450c3fe4f089eaa403434815eecdbd7
Thanks,
Kazu
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