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Message-ID: <CALJQGLkLBrgtiz1f=_NHZG5jtwn2TfzqB4yCgfxxmQWXbfN7dQ@mail.gmail.com>
Date: Thu, 18 May 2023 22:05:11 +0800
From: Yuwei Guan <ssawgyw@...il.com>
To: Anshuman Khandual <anshuman.khandual@....com>
Cc: rppt@...nel.org, akpm@...ux-foundation.org, tsahu@...ux.ibm.com,
linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] memblock: Add flags and nid info in memblock debugfs
Anshuman Khandual <anshuman.khandual@....com> 于2023年5月18日周四 18:12写道：
>
>
>
> On 5/18/23 14:44, Yuwei Guan wrote:
> > Currently, the memblock debugfs can display the count of memblock_type and
> > the base and end of the reg. However, when memblock_mark_*() or
> > memblock_set_node() is executed on some range, the information in the
> > existing debugfs cannot make it clear why the address is not consecutive.
> >
> > For example,
> > cat /sys/kernel/debug/memblock/memory
> > 0: 0x0000000080000000..0x00000000901fffff
> > 1: 0x0000000090200000..0x00000000905fffff
> > 2: 0x0000000090600000..0x0000000092ffffff
> > 3: 0x0000000093000000..0x00000000973fffff
> > 4: 0x0000000097400000..0x00000000b71fffff
> > 5: 0x00000000c0000000..0x00000000dfffffff
> > 6: 0x00000000e2500000..0x00000000f87fffff
> > 7: 0x00000000f8800000..0x00000000fa7fffff
> > 8: 0x00000000fa800000..0x00000000fd3effff
> > 9: 0x00000000fd3f0000..0x00000000fd3fefff
> > 10: 0x00000000fd3ff000..0x00000000fd7fffff
> > 11: 0x00000000fd800000..0x00000000fd901fff
> > 12: 0x00000000fd902000..0x00000000fd909fff
> > 13: 0x00000000fd90a000..0x00000000fd90bfff
> > 14: 0x00000000fd90c000..0x00000000ffffffff
> > 15: 0x0000000880000000..0x0000000affffffff
> >
> > So we can add flags and nid to this debugfs.
> >
> > For example,
> > cat /sys/kernel/debug/memblock/memory
> > 0: 0x0000000080000000..0x00000000901fffff NONE 0
> > 1: 0x0000000090200000..0x00000000905fffff NOMAP 0
> > 2: 0x0000000090600000..0x0000000092ffffff NONE 0
> > 3: 0x0000000093000000..0x00000000973fffff NOMAP 0
> > 4: 0x0000000097400000..0x00000000b71fffff NONE 0
> > 5: 0x00000000c0000000..0x00000000dfffffff NONE 0
> > 6: 0x00000000e2500000..0x00000000f87fffff NONE 0
> > 7: 0x00000000f8800000..0x00000000fa7fffff NOMAP 0
> > 8: 0x00000000fa800000..0x00000000fd3effff NONE 0
> > 9: 0x00000000fd3f0000..0x00000000fd3fefff NOMAP 0
> > 10: 0x00000000fd3ff000..0x00000000fd7fffff NONE 0
> > 11: 0x00000000fd800000..0x00000000fd901fff NOMAP 0
> > 12: 0x00000000fd902000..0x00000000fd909fff NONE 0
> > 13: 0x00000000fd90a000..0x00000000fd90bfff NOMAP 0
> > 14: 0x00000000fd90c000..0x00000000ffffffff NONE 0
> > 15: 0x0000000880000000..0x0000000affffffff NONE 0
>
> Although, Mike had suggested to keep these flags print last, above
> format looks good as well.
>
> >
> > Signed-off-by: Yuwei Guan <ssawgyw@...il.com>
> > ---
> > v3:
> > - show string value for each memblock flag
> > ---
> > mm/memblock.c | 12 +++++++++++-
> > 1 file changed, 11 insertions(+), 1 deletion(-)
> >
> > diff --git a/mm/memblock.c b/mm/memblock.c
> > index 511d4783dcf1..5fba53f98b2d 100644
> > --- a/mm/memblock.c
> > +++ b/mm/memblock.c
> > @@ -2143,13 +2143,23 @@ static int memblock_debug_show(struct seq_file *m, void *private)
> > struct memblock_region *reg;
> > int i;
> > phys_addr_t end;
> > + static const char flagname[BITS_PER_LONG][8] = {
> > + [0 ... (BITS_PER_LONG-1)] = "?",
>
> Minor nit -
>
> Although checkpatch does not complain, should there be spaces between
> the operator and operands e.g (BITS_PER_LONG - 1).
>
> > +
> > + [ilog2(MEMBLOCK_HOTPLUG)] = "HOTPLUG",
> > + [ilog2(MEMBLOCK_MIRROR)] = "MIRROR",
> > + [ilog2(MEMBLOCK_NOMAP)] = "NOMAP",
> > + [ilog2(MEMBLOCK_DRIVER_MANAGED)] = "DRV_MNG",
> > + };
>
> Also, BITS_PER_LONG sized array is really required here ? as there are
> just four available memblock flags.
>
Hi Anshuman,
The main reason to use BITS_PER_LONG is to reserve.
If the flagname buffer is (ilog2(MEMBLOCK_DRIVER_MANAGED) + 1),
memblock_flags adds a new attribute and does not add its name in debugfs,
it will cause an overflow.
But BITS_PER_LONG is too wasteful, so I implement a new solution.
Please help to check it.
struct memblock_type *type = m->private;
struct memblock_region *reg;
- int i;
+ int i, j;
phys_addr_t end;
+ static const char *flagname[] = {
+ [ilog2(MEMBLOCK_HOTPLUG)] = "HOTPLUG",
+ [ilog2(MEMBLOCK_MIRROR)] = "MIRROR",
+ [ilog2(MEMBLOCK_NOMAP)] = "NOMAP",
+ [ilog2(MEMBLOCK_DRIVER_MANAGED)] = "DRV_MNG",
+ };
for (i = 0; i < type->cnt; i++) {
reg = &type->regions[i];
end = reg->base + reg->size - 1;
seq_printf(m, "%4d: ", i);
- seq_printf(m, "%pa..%pa\n", ®->base, &end);
+ seq_printf(m, "%pa..%pa ", ®->base, &end);
+ seq_printf(m, "%4d ", memblock_get_region_node(reg));
+ if (reg->flags) {
+ for (j = 0; j < ARRAY_SIZE(flagname); j++) {
+ if (reg->flags & (1U << j)) {
+ seq_printf(m, "%s\n", flagname[j]);
+ break;
+ }
+ }
+ if (j == ARRAY_SIZE(flagname))
+ seq_printf(m, "%s\n", "UNKNOWN");
+ } else {
+ seq_printf(m, "%s\n", "NONE");
+ }
}
> >
> > for (i = 0; i < type->cnt; i++) {
> > reg = &type->regions[i];
> > end = reg->base + reg->size - 1;
> >
> > seq_printf(m, "%4d: ", i);
> > - seq_printf(m, "%pa..%pa\n", ®->base, &end);
> > + seq_printf(m, "%pa..%pa ", ®->base, &end);
> > + seq_printf(m, "%8s ", reg->flags ? flagname[ilog2(reg->flags)] : "NONE");
> > + seq_printf(m, "%4d\n", memblock_get_region_node(reg));
> > }
> > return 0;
> > }
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