[patch] tools, vm: new option to specify kpageflags file

From: David Rientjes
Date: Tue Jan 30 2018 - 18:01:08 EST


page-types currently hardcodes /proc/kpageflags as the file to parse.
This works when using the tool to examine the state of pageflags on the
same system, but does not allow storing a snapshot of pageflags at a given
time to debug issues nor on a different system.

This allows the user to specify a saved version of kpageflags with a new
page-types -F option.

Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
---
tools/vm/page-types.c | 26 ++++++++++++++++++++------
1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/tools/vm/page-types.c b/tools/vm/page-types.c
--- a/tools/vm/page-types.c
+++ b/tools/vm/page-types.c
@@ -172,6 +172,7 @@ static pid_t opt_pid; /* process to walk */
const char * opt_file; /* file or directory path */
static uint64_t opt_cgroup; /* cgroup inode */
static int opt_list_cgroup;/* list page cgroup */
+static const char * opt_kpageflags; /* kpageflags file to parse */

#define MAX_ADDR_RANGES 1024
static int nr_addr_ranges;
@@ -258,7 +259,7 @@ static int checked_open(const char *pathname, int flags)
* pagemap/kpageflags routines
*/

-static unsigned long do_u64_read(int fd, char *name,
+static unsigned long do_u64_read(int fd, const char *name,
uint64_t *buf,
unsigned long index,
unsigned long count)
@@ -283,7 +284,7 @@ static unsigned long kpageflags_read(uint64_t *buf,
unsigned long index,
unsigned long pages)
{
- return do_u64_read(kpageflags_fd, PROC_KPAGEFLAGS, buf, index, pages);
+ return do_u64_read(kpageflags_fd, opt_kpageflags, buf, index, pages);
}

static unsigned long kpagecgroup_read(uint64_t *buf,
@@ -293,7 +294,7 @@ static unsigned long kpagecgroup_read(uint64_t *buf,
if (kpagecgroup_fd < 0)
return pages;

- return do_u64_read(kpagecgroup_fd, PROC_KPAGEFLAGS, buf, index, pages);
+ return do_u64_read(kpagecgroup_fd, opt_kpageflags, buf, index, pages);
}

static unsigned long pagemap_read(uint64_t *buf,
@@ -743,7 +744,7 @@ static void walk_addr_ranges(void)
{
int i;

- kpageflags_fd = checked_open(PROC_KPAGEFLAGS, O_RDONLY);
+ kpageflags_fd = checked_open(opt_kpageflags, O_RDONLY);

if (!nr_addr_ranges)
add_addr_range(0, ULONG_MAX);
@@ -790,6 +791,7 @@ static void usage(void)
" -N|--no-summary Don't show summary info\n"
" -X|--hwpoison hwpoison pages\n"
" -x|--unpoison unpoison pages\n"
+" -F|--kpageflags kpageflags file to parse\n"
" -h|--help Show this usage message\n"
"flags:\n"
" 0x10 bitfield format, e.g.\n"
@@ -1013,7 +1015,7 @@ static void walk_page_cache(void)
{
struct stat st;

- kpageflags_fd = checked_open(PROC_KPAGEFLAGS, O_RDONLY);
+ kpageflags_fd = checked_open(opt_kpageflags, O_RDONLY);
pagemap_fd = checked_open("/proc/self/pagemap", O_RDONLY);
sigaction(SIGBUS, &sigbus_action, NULL);

@@ -1164,6 +1166,11 @@ static void parse_bits_mask(const char *optarg)
add_bits_filter(mask, bits);
}

+static void parse_kpageflags(const char *name)
+{
+ opt_kpageflags = name;
+}
+
static void describe_flags(const char *optarg)
{
uint64_t flags = parse_flag_names(optarg, 0);
@@ -1188,6 +1195,7 @@ static const struct option opts[] = {
{ "no-summary", 0, NULL, 'N' },
{ "hwpoison" , 0, NULL, 'X' },
{ "unpoison" , 0, NULL, 'x' },
+ { "kpageflags", 0, NULL, 'F' },
{ "help" , 0, NULL, 'h' },
{ NULL , 0, NULL, 0 }
};
@@ -1199,7 +1207,7 @@ int main(int argc, char *argv[])
page_size = getpagesize();

while ((c = getopt_long(argc, argv,
- "rp:f:a:b:d:c:ClLNXxh", opts, NULL)) != -1) {
+ "rp:f:a:b:d:c:ClLNXxF:h", opts, NULL)) != -1) {
switch (c) {
case 'r':
opt_raw = 1;
@@ -1242,6 +1250,9 @@ int main(int argc, char *argv[])
opt_unpoison = 1;
prepare_hwpoison_fd();
break;
+ case 'F':
+ parse_kpageflags(optarg);
+ break;
case 'h':
usage();
exit(0);
@@ -1251,6 +1262,9 @@ int main(int argc, char *argv[])
}
}

+ if (!opt_kpageflags)
+ opt_kpageflags = PROC_KPAGEFLAGS;
+
if (opt_cgroup || opt_list_cgroup)
kpagecgroup_fd = checked_open(PROC_KPAGECGROUP, O_RDONLY);