Hi Kazu,
Do you have a sample 5.3-rc1 vmlinux/vmcore pair that I can test this with?
You can send it to me offline.
Thanks,
Dave
----- Original Message -----
> Update for the "kmem -n" option on Linux 5.3-rc1 and later kernels that
> contain commit 326e1b8f83a4318b09033ef754f40c785aed5e68, titled
> "mm/sparsemem: introduce a SECTION_IS_EARLY flag". With this patch,
> the option displays a new state "E" for the flag, instead of printing
> incorrect mem_map addresses.
>
> Also update the confusing comment with the one from kernel commit
> def9b71ee651a6fee93a10734b94f93a69cdb2d4, titled "include/linux/mmzone.h:
> fix explanation of lower bits in the SPARSEMEM mem_map pointer".
>
> Signed-off-by: Kazuhito Hagio <k-hagio@xxxxxxxxxxxxx>
> ---
> help.c | 4 ++--
> memory.c | 17 ++++++++++++++---
> 2 files changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/help.c b/help.c
> index d5940f789ffd..a5218a701c01 100644
> --- a/help.c
> +++ b/help.c
> @@ -6597,8 +6597,8 @@ char *help_kmem[] = {
> " the cumulative, vm_event_states counter values if they exist.",
> " -n display memory node, memory section, and memory block data",
> " and state; the state of each memory section state is encoded",
> -" as \"P\", \"M\" and/or \"O\", meaning SECTION_MARKED_PRESENT,",
> -" SECTION_HAS_MEM_MAP and SECTION_IS_ONLINE.",
> +" as \"P\", \"M\", \"O\" and/or \"E\", meaning
> SECTION_MARKED_PRESENT,",
> +" SECTION_HAS_MEM_MAP, SECTION_IS_ONLINE and SECTION_IS_EARLY.",
> " -z displays per-zone memory statistics.",
> " -o displays each cpu's offset value that is added to per-cpu
> symbol",
> " values to translate them into kernel virtual addresses.",
> diff --git a/memory.c b/memory.c
> index 327e5355ec9c..ac7e73679405 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -17154,13 +17154,22 @@ nr_to_section(ulong nr)
>
> /*
> * We use the lower bits of the mem_map pointer to store
> - * a little bit of information. There should be at least
> - * 3 bits here due to 32-bit alignment.
> + * a little bit of information. The pointer is calculated
> + * as mem_map - section_nr_to_pfn(pnum). The result is
> + * aligned to the minimum alignment of the two values:
> + * 1. All mem_map arrays are page-aligned.
> + * 2. section_nr_to_pfn() always clears PFN_SECTION_SHIFT
> + * lowest bits. PFN_SECTION_SHIFT is arch-specific
> + * (equal SECTION_SIZE_BITS - PAGE_SHIFT), and the
> + * worst combination is powerpc with 256k pages,
> + * which results in PFN_SECTION_SHIFT equal 6.
> + * To sum it up, at least 6 bits are available.
> */
> #define SECTION_MARKED_PRESENT (1UL<<0)
> #define SECTION_HAS_MEM_MAP (1UL<<1)
> #define SECTION_IS_ONLINE (1UL<<2)
> -#define SECTION_MAP_LAST_BIT (1UL<<3)
> +#define SECTION_IS_EARLY (1UL<<3)
> +#define SECTION_MAP_LAST_BIT (1UL<<4)
> #define SECTION_MAP_MASK (~(SECTION_MAP_LAST_BIT-1))
>
>
> @@ -17257,6 +17266,8 @@ fill_mem_section_state(ulong state, char *buf)
> bufidx += sprintf(buf + bufidx, "%s", "M");
> if (state & SECTION_IS_ONLINE)
> bufidx += sprintf(buf + bufidx, "%s", "O");
> + if (state & SECTION_IS_EARLY)
> + bufidx += sprintf(buf + bufidx, "%s", "E");
> }
>
> void
> --
> 2.18.1
>
> --
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