On 12/28/24 01:03, Joanne Koong wrote:
Add support for reads/writes from buffers backed by hugepages.
This can be enabled through the '-h' flag. This flag should only be used
on systems where THP capabilities are enabled.
This is motivated by a recent bug that was due to faulty handling of
userspace buffers backed by hugepages. This patch is a mitigation
against problems like this in the future.
Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx>
---
ltp/fsx.c | 108 ++++++++++++++++++++++++++++++++++++++++++++++++------
1 file changed, 97 insertions(+), 11 deletions(-)
diff --git a/ltp/fsx.c b/ltp/fsx.c
index 41933354..fb6a9b31 100644
--- a/ltp/fsx.c
+++ b/ltp/fsx.c
@@ -190,6 +190,7 @@ int o_direct; /* -Z */
int aio = 0;
int uring = 0;
int mark_nr = 0;
+int hugepages = 0; /* -h flag */
int page_size;
int page_mask;
@@ -2471,7 +2472,7 @@ void
usage(void)
{
fprintf(stdout, "usage: %s",
- "fsx [-dfknqxyzBEFHIJKLORWXZ0]\n\
+ "fsx [-dfhknqxyzBEFHIJKLORWXZ0]\n\
[-b opnum] [-c Prob] [-g filldata] [-i logdev] [-j logid]\n\
[-l flen] [-m start:end] [-o oplen] [-p progressinterval]\n\
[-r readbdy] [-s style] [-t truncbdy] [-w writebdy]\n\
@@ -2484,6 +2485,7 @@ usage(void)
-e: pollute post-eof on size changes (default 0)\n\
-f: flush and invalidate cache after I/O\n\
-g X: write character X instead of random generated data\n\
+ -h hugepages: use buffers backed by hugepages for reads/writes\n\
-i logdev: do integrity testing, logdev is the dm log writes device\n\
-j logid: prefix debug log messsages with this id\n\
-k: do not truncate existing file and use its size as upper bound on file size\n\
@@ -2856,6 +2858,95 @@ keep_running(void)
return numops-- != 0;
}
+static long
+get_hugepage_size(void)
+{
+ const char str[] = "Hugepagesize:";
+ size_t str_len = sizeof(str) - 1;
+ unsigned int hugepage_size = 0;
+ char buffer[64];
+ FILE *file;
+
+ file = fopen("/proc/meminfo", "r");
+ if (!file) {
+ prterr("get_hugepage_size: fopen /proc/meminfo");
+ return -1;
+ }
+ while (fgets(buffer, sizeof(buffer), file)) {
+ if (strncmp(buffer, str, str_len) == 0) {
+ sscanf(buffer + str_len, "%u", &hugepage_size);
+ break;
+ }
+ }
+ fclose(file);
+ if (!hugepage_size) {
+ prterr("get_hugepage_size: failed to find "
+ "hugepage size in /proc/meminfo\n");
+ return -1;
+ }
+
+ /* convert from KiB to bytes */
+ return hugepage_size << 10;
Thanks for the change.
+}
+
+static void *
+init_hugepages_buf(unsigned len, int hugepage_size, int alignment)
+{
+ void *buf;
+ long buf_size = roundup(len, hugepage_size) + alignment;
+
+ if (posix_memalign(&buf, hugepage_size, buf_size)) {
+ prterr("posix_memalign for buf");
+ return NULL;
+ }
+ memset(buf, '\0', buf_size);
+ if (madvise(buf, buf_size, MADV_COLLAPSE)) {
+ prterr("madvise collapse for buf");
+ free(buf);
+ return NULL;
+ }
+
+ return buf;
+}
+
+static void
+init_buffers(void)
+{
+ int i;
+
+ original_buf = (char *) malloc(maxfilelen);
+ for (i = 0; i < maxfilelen; i++)
+ original_buf[i] = random() % 256;
+ if (hugepages) {
+ long hugepage_size = get_hugepage_size();
+ if (hugepage_size == -1) {
+ prterr("get_hugepage_size()");
+ exit(100);
+ }
+ good_buf = init_hugepages_buf(maxfilelen, hugepage_size, writebdy);
+ if (!good_buf) {
+ prterr("init_hugepages_buf failed for good_buf");
+ exit(101);
+ }
+
+ temp_buf = init_hugepages_buf(maxoplen, hugepage_size, readbdy);
+ if (!temp_buf) {
+ prterr("init_hugepages_buf failed for temp_buf");
+ exit(101);
+ }
+ } else {
+ unsigned long good_buf_len = maxfilelen + writebdy;
+ unsigned long temp_buf_len = maxoplen + readbdy;
+
+ good_buf = (char *) malloc(good_buf_len);
+ memset(good_buf, '\0', good_buf_len);
minor: maybe good_buf = (char *)calloc(1, good_buf_len); So we don't
need to use memset.
+ temp_buf = (char *) malloc(temp_buf_len);
+ memset(temp_buf, '\0', temp_buf_len);
+ }
+ good_buf = round_ptr_up(good_buf, writebdy, 0);
+ temp_buf = round_ptr_up(temp_buf, readbdy, 0);
+}
+
static struct option longopts[] = {
{"replay-ops", required_argument, 0, 256},
{"record-ops", optional_argument, 0, 255},
@@ -2883,7 +2974,7 @@ main(int argc, char **argv)
setvbuf(stdout, (char *)0, _IOLBF, 0); /* line buffered stdout */
while ((ch = getopt_long(argc, argv,
- "0b:c:de:fg:i:j:kl:m:no:p:qr:s:t:uw:xyABD:EFJKHzCILN:OP:RS:UWXZ",
+ "0b:c:de:fg:hi:j:kl:m:no:p:qr:s:t:uw:xyABD:EFJKHzCILN:OP:RS:UWXZ",
longopts, NULL)) != EOF)
switch (ch) {
case 'b':
@@ -2916,6 +3007,9 @@ main(int argc, char **argv)
case 'g':
filldata = *optarg;
break;
+ case 'h':
+ hugepages = 1;
+ break;
case 'i':
integrity = 1;
logdev = strdup(optarg);
@@ -3229,15 +3323,7 @@ main(int argc, char **argv)
exit(95);
}
}
- original_buf = (char *) malloc(maxfilelen);
- for (i = 0; i < maxfilelen; i++)
- original_buf[i] = random() % 256;
- good_buf = (char *) malloc(maxfilelen + writebdy);
- good_buf = round_ptr_up(good_buf, writebdy, 0);
- memset(good_buf, '\0', maxfilelen);
- temp_buf = (char *) malloc(maxoplen + readbdy);
- temp_buf = round_ptr_up(temp_buf, readbdy, 0);
- memset(temp_buf, '\0', maxoplen);
+ init_buffers();
if (lite) { /* zero entire existing file */
ssize_t written;
--
Nirjhar Roy
Linux Kernel Developer
IBM, Bangalore
