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mm, printk: introduce new format %pGt for page_type

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%pGp format is used to display 'flags' field of a struct page.  However,
some page flags (i.e.  PG_buddy, see page-flags.h for more details) are
stored in page_type field.  To display human-readable output of page_type,
introduce %pGt format.

It is important to note the meaning of bits are different in page_type. 
if page_type is 0xffffffff, no flags are set.  Setting PG_buddy
(0x00000080) flag results in a page_type of 0xffffff7f.  Clearing a bit
actually means setting a flag.  Bits in page_type are inverted when
displaying type names.

Only values for which page_type_has_type() returns true are considered as
page_type, to avoid confusion with mapcount values.  if it returns false,
only raw values are displayed and not page type names.

Link: https://lkml.kernel.org/r/20230130042514.2418-3-42.hyeyoo@gmail.com
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>	[vsprintf part]
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Hyeonggon Yoo
2023-01-30 13:25:13 +09:00
committed by Andrew Morton
parent e26fcc02c7
commit 4c85c0be3d
7 changed files with 78 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

26
lib/test_printf.c
View File

@@ -642,12 +642,26 @@ page_flags_test(int section, int node, int zone, int last_cpupid,
test(cmp_buf, "%pGp", &flags);
}
static void __init page_type_test(unsigned int page_type, const char *name,
char *cmp_buf)
{
unsigned long size;
size = scnprintf(cmp_buf, BUF_SIZE, "%#x(", page_type);
if (page_type_has_type(page_type))
size += scnprintf(cmp_buf + size, BUF_SIZE - size, "%s", name);
snprintf(cmp_buf + size, BUF_SIZE - size, ")");
test(cmp_buf, "%pGt", &page_type);
}
static void __init
flags(void)
{
unsigned long flags;
char *cmp_buffer;
gfp_t gfp;
unsigned int page_type;
cmp_buffer = kmalloc(BUF_SIZE, GFP_KERNEL);
if (!cmp_buffer)
@@ -687,6 +701,18 @@ flags(void)
gfp |= __GFP_HIGH;
test(cmp_buffer, "%pGg", &gfp);
page_type = ~0;
page_type_test(page_type, "", cmp_buffer);
page_type = 10;
page_type_test(page_type, "", cmp_buffer);
page_type = ~PG_buddy;
page_type_test(page_type, "buddy", cmp_buffer);
page_type = ~(PG_table | PG_buddy);
page_type_test(page_type, "table|buddy", cmp_buffer);
kfree(cmp_buffer);
}