diff mbox series

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

Message ID 20210215155141.47432-4-laoar.shao@gmail.com (mailing list archive)
State New, archived
Headers show
Series mm, vsprintf: dump full information of page flags in pGp | expand

Commit Message

Yafang Shao Feb. 15, 2021, 3:51 p.m. UTC
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@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
---
 Documentation/core-api/printk-formats.rst |  2 +-
 lib/test_printf.c                         | 60 +++++++++++++++++----
 lib/vsprintf.c                            | 66 +++++++++++++++++++++--
 3 files changed, 112 insertions(+), 16 deletions(-)

Comments

Yafang Shao Feb. 22, 2021, 9:59 a.m. UTC | #1
On Mon, Feb 15, 2021 at 11:53 PM Yafang Shao <laoar.shao@gmail.com> 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@gmail.com>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Joe Perches <joe@perches.com>
> Cc: Miaohe Lin <linmiaohe@huawei.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Cc: Matthew Wilcox <willy@infradead.org>
> Cc: Petr Mladek <pmladek@suse.com>
> ---
>  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 ?
Petr Mladek Feb. 22, 2021, 12:38 p.m. UTC | #2
Hello,

first, I am sorry for the late reply. I have marked the thread as
proceed by mistake last week...


On Mon 2021-02-15 23:51:41, Yafang Shao 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.
> 
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> +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);

I have found one more small issue.

The purpose of the flag-specific printk_spec is to define the format
how the value is printed. The name of the flag should be printed
using default_str_spec.

It works because the string is printed as-is with both
default_dec_spec and default_flag_spec. But it would be better
to use the string format.

> +		if (buf < end)
> +			*buf = '=';
> +		buf++;
> +		buf = number(buf, end, (flags >> pff[i].shift) & pff[i].mask,
> +			     *pff[i].spec);
> +
> +		append = true;
> +	}
> +
> +	return buf;
> +}

Otherwise, the patch looks to me. The issue is cosmetic and might be
fixed either by re-spinning just this patch or by a followup patch.
Either way, feel free to use:

Reviewed-by: Petr Mladek <pmladek@suse.com>

Another question where to push this change. It is pity the we
finalized it in the middle of the merge window. It has to spend
at least few days in linux-next.

I would like to hear from Andy before I push it into linux-next.
There is still theoretical chance to get it into 5.12 when Linus
prolongs the merge window by one week. it has been delayed by
a long lasting power outage.

Best Regards,
Petr
Matthew Wilcox Feb. 22, 2021, 1:39 p.m. UTC | #3
On Mon, Feb 22, 2021 at 01:38:17PM +0100, Petr Mladek wrote:
> Another question where to push this change. It is pity the we
> finalized it in the middle of the merge window. It has to spend
> at least few days in linux-next.
> 
> I would like to hear from Andy before I push it into linux-next.
> There is still theoretical chance to get it into 5.12 when Linus
> prolongs the merge window by one week. it has been delayed by
> a long lasting power outage.

Usually new code has to be in linux-next by -rc5 or so.  This is
definitely too late for 5.12, but it's nice and early for 5.13!
Yafang Shao Feb. 23, 2021, 1:10 a.m. UTC | #4
On Mon, Feb 22, 2021 at 8:38 PM Petr Mladek <pmladek@suse.com> wrote:
>
> Hello,
>
> first, I am sorry for the late reply. I have marked the thread as
> proceed by mistake last week...
>
>
> On Mon 2021-02-15 23:51:41, Yafang Shao 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.
> >
> > --- a/lib/vsprintf.c
> > +++ b/lib/vsprintf.c
> > +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);
>
> I have found one more small issue.
>
> The purpose of the flag-specific printk_spec is to define the format
> how the value is printed. The name of the flag should be printed
> using default_str_spec.
>
> It works because the string is printed as-is with both
> default_dec_spec and default_flag_spec. But it would be better
> to use the string format.
>

Thanks for the explanation.

> > +             if (buf < end)
> > +                     *buf = '=';
> > +             buf++;
> > +             buf = number(buf, end, (flags >> pff[i].shift) & pff[i].mask,
> > +                          *pff[i].spec);
> > +
> > +             append = true;
> > +     }
> > +
> > +     return buf;
> > +}
>
> Otherwise, the patch looks to me. The issue is cosmetic and might be
> fixed either by re-spinning just this patch or by a followup patch.

I will send a separate followup patch.

> Either way, feel free to use:
>
> Reviewed-by: Petr Mladek <pmladek@suse.com>
>

Thanks

> Another question where to push this change. It is pity the we
> finalized it in the middle of the merge window. It has to spend
> at least few days in linux-next.
>
> I would like to hear from Andy before I push it into linux-next.
> There is still theoretical chance to get it into 5.12 when Linus
> prolongs the merge window by one week. it has been delayed by
> a long lasting power outage.
>
> Best Regards,
> Petr
Petr Mladek March 3, 2021, 3:43 p.m. UTC | #5
On Mon 2021-02-22 13:39:56, Matthew Wilcox wrote:
> On Mon, Feb 22, 2021 at 01:38:17PM +0100, Petr Mladek wrote:
> > Another question where to push this change. It is pity the we
> > finalized it in the middle of the merge window. It has to spend
> > at least few days in linux-next.
> > 
> > I would like to hear from Andy before I push it into linux-next.
> > There is still theoretical chance to get it into 5.12 when Linus
> > prolongs the merge window by one week. it has been delayed by
> > a long lasting power outage.
> 
> Usually new code has to be in linux-next by -rc5 or so.  This is
> definitely too late for 5.12, but it's nice and early for 5.13!

OK, I am going to queue it for 5.13 the following week unless anyone
speaks against it in the meantime.

Best Regards,
Petr
Petr Mladek March 9, 2021, 10:21 a.m. UTC | #6
On Wed 2021-03-03 16:43:25, Petr Mladek wrote:
> On Mon 2021-02-22 13:39:56, Matthew Wilcox wrote:
> > On Mon, Feb 22, 2021 at 01:38:17PM +0100, Petr Mladek wrote:
> > > Another question where to push this change. It is pity the we
> > > finalized it in the middle of the merge window. It has to spend
> > > at least few days in linux-next.
> > > 
> > > I would like to hear from Andy before I push it into linux-next.
> > > There is still theoretical chance to get it into 5.12 when Linus
> > > prolongs the merge window by one week. it has been delayed by
> > > a long lasting power outage.
> > 
> > Usually new code has to be in linux-next by -rc5 or so.  This is
> > definitely too late for 5.12, but it's nice and early for 5.13!
> 
> OK, I am going to queue it for 5.13 the following week unless anyone
> speaks against it in the meantime.

The patchset is committed in printk/linux.git,
branch for-5.13-vsprintf-pgp.

Best Regards,
Petr
diff mbox series

Patch

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;