Re: [PATCH v5 3/3] vsprintf: dump full information of page flags in pGp

From: Yafang Shao
Date: Mon Feb 22 2021 - 05:05:46 EST

On Mon, Feb 15, 2021 at 11:53 PM Yafang Shao <laoar.shao@xxxxxxxxx> wrote:
>
> Currently the pGp only shows the names of page flags, rather than
> the full information including section, node, zone, last cpupid and
> kasan tag. While it is not easy to parse these information manually
> because there're so many flavors. Let's interpret them in pGp as well.
>
> To be compitable with the existed format of pGp, the new introduced ones
> also use '|' as the separator, then the user tools parsing pGp won't
> need to make change, suggested by Matthew. The new information is
> tracked onto the end of the existed one.
>
> One example of the output in mm/slub.c as follows,
> - Before the patch,
> [ 6343.396602] Slab 0x000000004382e02b objects=33 used=3 fp=0x000000009ae06ffc flags=0x17ffffc0010200(slab|head)
>
> - After the patch,
> [ 8448.272530] Slab 0x0000000090797883 objects=33 used=3 fp=0x00000000790f1c26 flags=0x17ffffc0010200(slab|head|node=0|zone=2|lastcpupid=0x1fffff)
>
> The documentation and test cases are also updated. The output of the
> test cases as follows,
> [11585.830272] test_printf: loaded.
> [11585.830454] test_printf: all 388 tests passed
> [11585.831401] test_printf: unloaded.
>
> Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
> Cc: David Hildenbrand <david@xxxxxxxxxx>
> Cc: Joe Perches <joe@xxxxxxxxxxx>
> Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
> Cc: Vlastimil Babka <vbabka@xxxxxxx>
> Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
> Cc: Petr Mladek <pmladek@xxxxxxxx>
> ---
> Documentation/core-api/printk-formats.rst | 2 +-
> lib/test_printf.c | 60 +++++++++++++++++----
> lib/vsprintf.c | 66 +++++++++++++++++++++--
> 3 files changed, 112 insertions(+), 16 deletions(-)
>
> diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
> index 160e710d992f..00d07c7eefd4 100644
> --- a/Documentation/core-api/printk-formats.rst
> +++ b/Documentation/core-api/printk-formats.rst
> @@ -540,7 +540,7 @@ Flags bitfields such as page flags, gfp_flags
>
> ::
>
> - %pGp referenced|uptodate|lru|active|private
> + %pGp referenced|uptodate|lru|active|private|node=0|zone=2|lastcpupid=0x1fffff
> %pGg GFP_USER|GFP_DMA32|GFP_NOWARN
> %pGv read|exec|mayread|maywrite|mayexec|denywrite
>
> diff --git a/lib/test_printf.c b/lib/test_printf.c
> index 7ac87f18a10f..148773dfe97a 100644
> --- a/lib/test_printf.c
> +++ b/lib/test_printf.c
> @@ -569,24 +569,68 @@ netdev_features(void)
> {
> }
>
> +static void __init
> +page_flags_test(int section, int node, int zone, int last_cpupid,
> + int kasan_tag, int flags, const char *name, char *cmp_buf)
> +{
> + unsigned long page_flags = 0;
> + unsigned long size = 0;
> +
> + flags &= BIT(NR_PAGEFLAGS) - 1;
> + if (flags) {
> + page_flags |= flags;
> + snprintf(cmp_buf + size, BUF_SIZE - size, "%s|", name);
> + size = strlen(cmp_buf);
> + }
> +
> +#ifdef SECTION_IN_PAGE_FLAGS
> + page_flags |= (sec & SECTIONS_MASK) << SECTIONS_PGSHIFT;
> + snprintf(cmp_buf + size, BUF_SIZE - size, "section=%#x|", sec);
> + size = strlen(cmp_buf);
> +#endif
> +
> + page_flags |= ((node & NODES_MASK) << NODES_PGSHIFT) |
> + ((zone & ZONES_MASK) << ZONES_PGSHIFT);
> + snprintf(cmp_buf + size, BUF_SIZE - size, "node=%d|zone=%d", node, zone);
> + size = strlen(cmp_buf);
> +
> +#ifndef LAST_CPUPID_NOT_IN_PAGE_FLAGS
> + page_flags |= (last_cpupid & LAST_CPUPID_MASK) << LAST_CPUPID_PGSHIFT;
> + snprintf(cmp_buf + size, BUF_SIZE - size, "|lastcpupid=%#x", last_cpupid);
> + size = strlen(cmp_buf);
> +#endif
> +
> +#if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS)
> + page_flags |= (tag & KASAN_TAG_MASK) << KASAN_TAG_PGSHIFT;
> + snprintf(cmp_buf + size, BUF_SIZE - size, "|kasantag=%#x", tag);
> + size = strlen(cmp_buf);
> +#endif
> +
> + test(cmp_buf, "%pGp", &page_flags);
> +}
> +
> static void __init
> flags(void)
> {
> unsigned long flags;
> - gfp_t gfp;
> char *cmp_buffer;
> + gfp_t gfp;
> +
> + cmp_buffer = kmalloc(BUF_SIZE, GFP_KERNEL);
> + if (!cmp_buffer)
> + return;
>
> flags = 0;
> - test("", "%pGp", &flags);
> + page_flags_test(0, 0, 0, 0, 0, flags, "", cmp_buffer);
>
> - /* Page flags should filter the zone id */
> flags = 1UL << NR_PAGEFLAGS;
> - test("", "%pGp", &flags);
> + page_flags_test(0, 0, 0, 0, 0, flags, "", cmp_buffer);
>
> flags |= 1UL << PG_uptodate | 1UL << PG_dirty | 1UL << PG_lru
> | 1UL << PG_active | 1UL << PG_swapbacked;
> - test("uptodate|dirty|lru|active|swapbacked", "%pGp", &flags);
> -
> + page_flags_test(1, 1, 1, 0x1fffff, 1, flags,
> + "uptodate|dirty|lru|active|swapbacked",
> + cmp_buffer);
>
> flags = VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC
> | VM_DENYWRITE;
> @@ -601,10 +645,6 @@ flags(void)
> gfp = __GFP_ATOMIC;
> test("__GFP_ATOMIC", "%pGg", &gfp);
>
> - cmp_buffer = kmalloc(BUF_SIZE, GFP_KERNEL);
> - if (!cmp_buffer)
> - return;
> -
> /* Any flags not translated by the table should remain numeric */
> gfp = ~__GFP_BITS_MASK;
> snprintf(cmp_buffer, BUF_SIZE, "%#lx", (unsigned long) gfp);
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index 3b53c73580c5..0dc776f7dfa4 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -1916,6 +1916,66 @@ char *format_flags(char *buf, char *end, unsigned long flags,
> return buf;
> }
>
> +struct page_flags_fields {
> + int width;
> + int shift;
> + int mask;
> + const struct printf_spec *spec;
> + const char *name;
> +};
> +
> +static const struct page_flags_fields pff[] = {
> + {SECTIONS_WIDTH, SECTIONS_PGSHIFT, SECTIONS_MASK,
> + &default_dec_spec, "section"},
> + {NODES_WIDTH, NODES_PGSHIFT, NODES_MASK,
> + &default_dec_spec, "node"},
> + {ZONES_WIDTH, ZONES_PGSHIFT, ZONES_MASK,
> + &default_dec_spec, "zone"},
> + {LAST_CPUPID_WIDTH, LAST_CPUPID_PGSHIFT, LAST_CPUPID_MASK,
> + &default_flag_spec, "lastcpupid"},
> + {KASAN_TAG_WIDTH, KASAN_TAG_PGSHIFT, KASAN_TAG_MASK,
> + &default_flag_spec, "kasantag"},
> +};
> +
> +static
> +char *format_page_flags(char *buf, char *end, unsigned long flags)
> +{
> + unsigned long main_flags = flags & (BIT(NR_PAGEFLAGS) - 1);
> + bool append = false;
> + int i;
> +
> + /* Page flags from the main area. */
> + if (main_flags) {
> + buf = format_flags(buf, end, main_flags, pageflag_names);
> + append = true;
> + }
> +
> + /* Page flags from the fields area */
> + for (i = 0; i < ARRAY_SIZE(pff); i++) {
> + /* Skip undefined fields. */
> + if (!pff[i].width)
> + continue;
> +
> + /* Format: Flag Name + '=' (equals sign) + Number + '|' (separator) */
> + if (append) {
> + if (buf < end)
> + *buf = '|';
> + buf++;
> + }
> +
> + buf = string(buf, end, pff[i].name, *pff[i].spec);
> + if (buf < end)
> + *buf = '=';
> + buf++;
> + buf = number(buf, end, (flags >> pff[i].shift) & pff[i].mask,
> + *pff[i].spec);
> +
> + append = true;
> + }
> +
> + return buf;
> +}
> +
> static noinline_for_stack
> char *flags_string(char *buf, char *end, void *flags_ptr,
> struct printf_spec spec, const char *fmt)
> @@ -1928,11 +1988,7 @@ char *flags_string(char *buf, char *end, void *flags_ptr,
>
> switch (fmt[1]) {
> case 'p':
> - flags = *(unsigned long *)flags_ptr;
> - /* Remove zone id */
> - flags &= (1UL << NR_PAGEFLAGS) - 1;
> - names = pageflag_names;
> - break;
> + return format_page_flags(buf, end, *(unsigned long *)flags_ptr);
> case 'v':
> flags = *(unsigned long *)flags_ptr;
> names = vmaflag_names;
> --
> 2.18.2
>

Hello,

Any comments on this new version ?

--
Thanks
Yafang