| Message ID | 20250118004759.2772065-2-joannelkoong@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | fstests: test reads/writes from hugepages-backed buffers | expand |
On Fri, Jan 17, 2025 at 04:47:58PM -0800, 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@gmail.com> > Reviewed-by: Brian Foster <bfoster@redhat.com> > --- > ltp/fsx.c | 165 +++++++++++++++++++++++++++++++++++++++++++++++++----- > 1 file changed, 152 insertions(+), 13 deletions(-) > > diff --git a/ltp/fsx.c b/ltp/fsx.c > index 41933354..1513755f 100644 > --- a/ltp/fsx.c > +++ b/ltp/fsx.c > @@ -190,6 +190,16 @@ int o_direct; /* -Z */ > int aio = 0; > int uring = 0; > int mark_nr = 0; > +int hugepages = 0; /* -h flag */ > + > +/* Stores info needed to periodically collapse hugepages */ > +struct hugepages_collapse_info { > + void *orig_good_buf; > + long good_buf_size; > + void *orig_temp_buf; > + long temp_buf_size; > +}; > +struct hugepages_collapse_info hugepages_info; > > int page_size; > int page_mask; > @@ -2471,7 +2481,7 @@ 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\ > @@ -2483,8 +2493,11 @@ usage(void) > -d: debug output for all operations\n\ > -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\ > - -i logdev: do integrity testing, logdev is the dm log writes device\n\ > + -g X: write character X instead of random generated data\n" > +#ifdef MADV_COLLAPSE > +" -h hugepages: use buffers backed by hugepages for reads/writes\n" > +#endif > +" -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\ > -l flen: the upper bound on file size (default 262144)\n\ > @@ -2833,11 +2846,40 @@ __test_fallocate(int mode, const char *mode_str) > #endif > } > > +/* > + * Reclaim may break up hugepages, so do a best-effort collapse every once in > + * a while. > + */ > +static void > +collapse_hugepages(void) > +{ > +#ifdef MADV_COLLAPSE > + int interval = 1 << 14; /* 16k */ > + int ret; > + > + if (numops && (numops & (interval - 1)) == 0) { I wonder if this could be collapsed to: /* re-collapse every 16k fsxops after we start */ if (!numops || (numops & ((1U << 14) - 1))) return; ret = madvise(...); But my guess is that the compiler is smart enough to realize that interval never changes and fold it into the test expression? <shrug> Not that passionate either way. :) > + ret = madvise(hugepages_info.orig_good_buf, > + hugepages_info.good_buf_size, MADV_COLLAPSE); > + if (ret) > + prt("collapsing hugepages for good_buf failed (numops=%llu): %s\n", > + numops, strerror(errno)); > + ret = madvise(hugepages_info.orig_temp_buf, > + hugepages_info.temp_buf_size, MADV_COLLAPSE); > + if (ret) > + prt("collapsing hugepages for temp_buf failed (numops=%llu): %s\n", > + numops, strerror(errno)); > + } > +#endif > +} > + > bool > keep_running(void) > { > int ret; > > + if (hugepages) > + collapse_hugepages(); > + > if (deadline.tv_nsec) { > struct timespec now; > > @@ -2856,6 +2898,103 @@ 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; > +} > + > +static void * > +init_hugepages_buf(unsigned len, int hugepage_size, int alignment, long *buf_size) > +{ > + void *buf = NULL; > +#ifdef MADV_COLLAPSE > + int ret; > + long size = roundup(len, hugepage_size) + alignment; > + > + ret = posix_memalign(&buf, hugepage_size, size); > + if (ret) { > + prterr("posix_memalign for buf"); > + return NULL; > + } > + memset(buf, '\0', size); > + ret = madvise(buf, size, MADV_COLLAPSE); > + if (ret) { > + prterr("madvise collapse for buf"); > + free(buf); > + return NULL; > + } > + > + *buf_size = size; > +#endif > + 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(102); > + } > + good_buf = init_hugepages_buf(maxfilelen, hugepage_size, writebdy, > + &hugepages_info.good_buf_size); > + if (!good_buf) { > + prterr("init_hugepages_buf failed for good_buf"); > + exit(103); > + } > + hugepages_info.orig_good_buf = good_buf; > + > + temp_buf = init_hugepages_buf(maxoplen, hugepage_size, readbdy, > + &hugepages_info.temp_buf_size); > + if (!temp_buf) { > + prterr("init_hugepages_buf failed for temp_buf"); > + exit(103); > + } > + hugepages_info.orig_temp_buf = temp_buf; > + } else { > + unsigned long good_buf_len = maxfilelen + writebdy; > + unsigned long temp_buf_len = maxoplen + readbdy; > + > + good_buf = calloc(1, good_buf_len); > + temp_buf = calloc(1, 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 +3022,7 @@ 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 +3055,14 @@ main(int argc, char **argv) > case 'g': > filldata = *optarg; > break; > + case 'h': > +#ifndef MADV_COLLAPSE > + fprintf(stderr, "MADV_COLLAPSE not supported. " > + "Can't support -h\n"); > + exit(86); Excessive indenting here. With those fixed up, Reviewed-by: "Darrick J. Wong" <djwong@kernel.org> --D > +#endif > + hugepages = 1; > + break; > case 'i': > integrity = 1; > logdev = strdup(optarg); > @@ -3229,15 +3376,7 @@ 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; > > -- > 2.47.1 > >
diff --git a/ltp/fsx.c b/ltp/fsx.c index 41933354..1513755f 100644 --- a/ltp/fsx.c +++ b/ltp/fsx.c @@ -190,6 +190,16 @@ int o_direct; /* -Z */ int aio = 0; int uring = 0; int mark_nr = 0; +int hugepages = 0; /* -h flag */ + +/* Stores info needed to periodically collapse hugepages */ +struct hugepages_collapse_info { + void *orig_good_buf; + long good_buf_size; + void *orig_temp_buf; + long temp_buf_size; +}; +struct hugepages_collapse_info hugepages_info; int page_size; int page_mask; @@ -2471,7 +2481,7 @@ 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\ @@ -2483,8 +2493,11 @@ usage(void) -d: debug output for all operations\n\ -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\ - -i logdev: do integrity testing, logdev is the dm log writes device\n\ + -g X: write character X instead of random generated data\n" +#ifdef MADV_COLLAPSE +" -h hugepages: use buffers backed by hugepages for reads/writes\n" +#endif +" -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\ -l flen: the upper bound on file size (default 262144)\n\ @@ -2833,11 +2846,40 @@ __test_fallocate(int mode, const char *mode_str) #endif } +/* + * Reclaim may break up hugepages, so do a best-effort collapse every once in + * a while. + */ +static void +collapse_hugepages(void) +{ +#ifdef MADV_COLLAPSE + int interval = 1 << 14; /* 16k */ + int ret; + + if (numops && (numops & (interval - 1)) == 0) { + ret = madvise(hugepages_info.orig_good_buf, + hugepages_info.good_buf_size, MADV_COLLAPSE); + if (ret) + prt("collapsing hugepages for good_buf failed (numops=%llu): %s\n", + numops, strerror(errno)); + ret = madvise(hugepages_info.orig_temp_buf, + hugepages_info.temp_buf_size, MADV_COLLAPSE); + if (ret) + prt("collapsing hugepages for temp_buf failed (numops=%llu): %s\n", + numops, strerror(errno)); + } +#endif +} + bool keep_running(void) { int ret; + if (hugepages) + collapse_hugepages(); + if (deadline.tv_nsec) { struct timespec now; @@ -2856,6 +2898,103 @@ 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; +} + +static void * +init_hugepages_buf(unsigned len, int hugepage_size, int alignment, long *buf_size) +{ + void *buf = NULL; +#ifdef MADV_COLLAPSE + int ret; + long size = roundup(len, hugepage_size) + alignment; + + ret = posix_memalign(&buf, hugepage_size, size); + if (ret) { + prterr("posix_memalign for buf"); + return NULL; + } + memset(buf, '\0', size); + ret = madvise(buf, size, MADV_COLLAPSE); + if (ret) { + prterr("madvise collapse for buf"); + free(buf); + return NULL; + } + + *buf_size = size; +#endif + 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(102); + } + good_buf = init_hugepages_buf(maxfilelen, hugepage_size, writebdy, + &hugepages_info.good_buf_size); + if (!good_buf) { + prterr("init_hugepages_buf failed for good_buf"); + exit(103); + } + hugepages_info.orig_good_buf = good_buf; + + temp_buf = init_hugepages_buf(maxoplen, hugepage_size, readbdy, + &hugepages_info.temp_buf_size); + if (!temp_buf) { + prterr("init_hugepages_buf failed for temp_buf"); + exit(103); + } + hugepages_info.orig_temp_buf = temp_buf; + } else { + unsigned long good_buf_len = maxfilelen + writebdy; + unsigned long temp_buf_len = maxoplen + readbdy; + + good_buf = calloc(1, good_buf_len); + temp_buf = calloc(1, 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 +3022,7 @@ 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 +3055,14 @@ main(int argc, char **argv) case 'g': filldata = *optarg; break; + case 'h': +#ifndef MADV_COLLAPSE + fprintf(stderr, "MADV_COLLAPSE not supported. " + "Can't support -h\n"); + exit(86); +#endif + hugepages = 1; + break; case 'i': integrity = 1; logdev = strdup(optarg); @@ -3229,15 +3376,7 @@ 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;