[LTP] [PATCH v4] hugetlb/hugemmap: add new testcase hugemmap06.c
Helge Deller
deller@gmx.de
Mon Dec 21 14:36:39 CET 2015
On 21.12.2015 12:16, Li Wang wrote:
> Description of Problem:
> There is a race condition if we map a same file on different processes.
> Region tracking is protected by mmap_sem and hugetlb_instantiation_mutex.
> When we do mmap, we don't grab a hugetlb_instantiation_mutex, but only
> mmap_sem (exclusively). This doesn't prevent other tasks from modifying
> the region structure, so it can be modified by two processes concurrently.
>
> Testcase hugemmap06.c is the trigger to cause system crash:
> crash> bt -s
> PID: 4492 TASK: ffff88033e437520 CPU: 2 COMMAND: "hugemmap06"
> #0 [ffff88033dbb3960] machine_kexec+395 at ffffffff8103d1ab
> #1 [ffff88033dbb39c0] crash_kexec+114 at ffffffff810cc4f2
> #2 [ffff88033dbb3a90] oops_end+192 at ffffffff8153c840
> #3 [ffff88033dbb3ac0] die+91 at ffffffff81010f5b
> #4 [ffff88033dbb3af0] do_general_protection+338 at ffffffff8153c332
> #5 [ffff88033dbb3b20] general_protection+37 at ffffffff8153bb05
> [exception RIP: list_del+40]
> RIP: ffffffff812a3598 RSP: ffff88033dbb3bd8 RFLAGS: 00010292
> RAX: dead000000100100 RBX: ffff88013cf37340 RCX: 0000000000002dc2
> RDX: dead000000200200 RSI: 0000000000000046 RDI: 0000000000000009
> RBP: ffff88033dbb3be8 R8: 0000000000015598 R9: 0000000000000000
> R10: 000000000000000f R11: 0000000000000009 R12: 000000000000000a
> R13: ffff88033d64b9e8 R14: ffff88033e5b9720 R15: ffff88013cf37340
> ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0000
> #6 [ffff88033dbb3bf0] region_add+154 at ffffffff811698da
> #7 [ffff88033dbb3c40] alloc_huge_page+669 at ffffffff8116a61d
> #8 [ffff88033dbb3ce0] hugetlb_fault+1083 at ffffffff8116b9bb
> #9 [ffff88033dbb3d90] handle_mm_fault+917 at ffffffff81153295
> #10 [ffff88033dbb3e00] __do_page_fault+326 at ffffffff8104f156
> #11 [ffff88033dbb3f20] do_page_fault+62 at ffffffff8153e78e
> #12 [ffff88033dbb3f50] page_fault+37 at ffffffff8153bb35
> RIP: 00000000004027c6 RSP: 00007f7cadef9e80 RFLAGS: 00010297
> RAX: 000000005a49238f RBX: 00007ffcb2d19320 RCX: 000000357498e084
> RDX: 000000357498e0b0 RSI: 00007f7cadef9e5c RDI: 000000357498e4e0
> RBP: 0000000000000008 R8: 000000357498e0a0 R9: 000000357498e100
> R10: 00007f7cadefa9d0 R11: 0000000000000206 R12: 0000000000000007
> R13: 0000000000000002 R14: 0000000000000003 R15: 00002aaaac000000
> ORIG_RAX: ffffffffffffffff CS: 0033 SS: 002b
>
> The fix are all these below commits:
> f522c3ac00(mm, hugetlb: change variable name reservations to resv)
> 9119a41e90(mm, hugetlb: unify region structure handling)
> 7b24d8616b(mm, hugetlb: fix race in region tracking)
> 1406ec9ba6(mm, hugetlb: improve, cleanup resv_map parameters)
>
> Signed-off-by: Li Wang <liwang@redhat.com>
> ---
>
> Notes:
> v3 --> v4
> - declare sz type and assign value at the same line
> - change 'void *addr' to 'char * addr' in the mp struct
> - take use of 'mmap_sz->addr + ...' in a clean way
> - remove the useless pthread_join
> - fix a tpyo 'mremap'
>
> runtest/hugetlb | 1 +
> testcases/kernel/mem/.gitignore | 1 +
> testcases/kernel/mem/hugetlb/hugemmap/Makefile | 2 +
> testcases/kernel/mem/hugetlb/hugemmap/hugemmap06.c | 175 +++++++++++++++++++++
> 4 files changed, 179 insertions(+)
> create mode 100644 testcases/kernel/mem/hugetlb/hugemmap/hugemmap06.c
>
> diff --git a/runtest/hugetlb b/runtest/hugetlb
> index 2e9f215..ac24513 100644
> --- a/runtest/hugetlb
> +++ b/runtest/hugetlb
> @@ -2,6 +2,7 @@ hugemmap01 hugemmap01
> hugemmap02 hugemmap02
> hugemmap04 hugemmap04
> hugemmap05 hugemmap05
> +hugemmap06 hugemmap06
> hugemmap05_1 hugemmap05 -m
> hugemmap05_2 hugemmap05 -s
> hugemmap05_3 hugemmap05 -s -m
> diff --git a/testcases/kernel/mem/.gitignore b/testcases/kernel/mem/.gitignore
> index 4702377..ac8e6d8 100644
> --- a/testcases/kernel/mem/.gitignore
> +++ b/testcases/kernel/mem/.gitignore
> @@ -3,6 +3,7 @@
> /hugetlb/hugemmap/hugemmap02
> /hugetlb/hugemmap/hugemmap04
> /hugetlb/hugemmap/hugemmap05
> +/hugetlb/hugemmap/hugemmap06
> /hugetlb/hugeshmat/hugeshmat01
> /hugetlb/hugeshmat/hugeshmat02
> /hugetlb/hugeshmat/hugeshmat03
> diff --git a/testcases/kernel/mem/hugetlb/hugemmap/Makefile b/testcases/kernel/mem/hugetlb/hugemmap/Makefile
> index f51f6b9..2473aca 100644
> --- a/testcases/kernel/mem/hugetlb/hugemmap/Makefile
> +++ b/testcases/kernel/mem/hugetlb/hugemmap/Makefile
> @@ -25,3 +25,5 @@ top_srcdir ?= ../../../../..
> include $(top_srcdir)/include/mk/testcases.mk
> include $(abs_srcdir)/../Makefile.inc
> include $(top_srcdir)/include/mk/generic_leaf_target.mk
> +
> +hugemmap06: CFLAGS+=-pthread
> diff --git a/testcases/kernel/mem/hugetlb/hugemmap/hugemmap06.c b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap06.c
> new file mode 100644
> index 0000000..e52b21d
> --- /dev/null
> +++ b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap06.c
> @@ -0,0 +1,175 @@
> +/*
> + * Copyright (c) 2015 Red Hat, Inc.
> + *
> + * This program is free software: you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation, either version 3 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program. If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +/*
> + * DESCRIPTION
> + *
> + * There is a race condition if we map a same file on different processes.
> + * Region tracking is protected by mmap_sem and hugetlb_instantiation_mutex.
> + * When we do mmap, we don't grab a hugetlb_instantiation_mutex, but only
> + * mmap_sem (exclusively). This doesn't prevent other tasks from modifying
> + * the region structure, so it can be modified by two processes concurrently.
> + *
> + * This bug was fixed on stable kernel by commits:
> + * f522c3ac00(mm, hugetlb: change variable name reservations to resv)
> + * 9119a41e90(mm, hugetlb: unify region structure handling)
> + * 7b24d8616b(mm, hugetlb: fix race in region tracking)
> + * 1406ec9ba6(mm, hugetlb: improve, cleanup resv_map parameters)
> + *
> + * AUTHOR:
> + * Herton R. Krzesinski <herton@redhat.com>
> + * Li Wang <liwang@redhat.com>
> + */
> +
> +#define _GNU_SOURCE
> +#include <errno.h>
> +#include <pthread.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <sys/mman.h>
> +#include <sys/types.h>
> +#include <unistd.h>
> +
> +#include "test.h"
> +#include "mem.h"
> +#include "hugetlb.h"
> +
> +char *TCID = "hugemmap06";
> +int TST_TOTAL = 5;
> +
> +static long hpage_size;
> +static long hugepages;
> +
> +struct mp {
> + char *addr;
> + int sz;
> +};
> +
> +#define ARSZ 50
> +
> +void setup(void)
> +{
> + tst_require_root();
> + check_hugepage();
> +
> + hpage_size = read_meminfo("Hugepagesize:") * 1024;
> + orig_hugepages = get_sys_tune("nr_hugepages");
> +
> + hugepages = (ARSZ + 1) * TST_TOTAL;
> +
> + if (hugepages * read_meminfo("Hugepagesize:") > read_meminfo("MemTotal:"))
> + tst_brkm(TCONF, NULL, "System RAM is not enough to test.");
Just a general note:
What happens on architectures where no hugepages are available?
Maybe you should add a check and return TCONF() in those cases?
I think this is missing for the other existing hugepage testcases as well...
Helge
> +
> + set_sys_tune("nr_hugepages", hugepages, 1);
> +
> + TEST_PAUSE;
> +}
> +
> +void cleanup(void)
> +{
> + set_sys_tune("nr_hugepages", orig_hugepages, 0);
> +}
> +
> +void *thr(void *arg)
> +{
> + struct mp *mmap_sz = arg;
> + int i, lim, a, b, c;
> +
> + srand(time(NULL));
> + lim = rand() % 10;
> + for (i = 0; i < lim; i++) {
> + a = rand() % mmap_sz->sz;
> + for (c = 0; c <= a; c++) {
> + b = rand() % mmap_sz->sz;
> + *(mmap_sz->addr + b * hpage_size) = rand();
> + }
> + }
> + return NULL;
> +}
> +
> +void do_mmap(void)
> +{
> + int i, sz = ARSZ + 1;
> + void *addr, *new_addr;
> + struct mp mmap_sz[ARSZ];
> + pthread_t tid[ARSZ];
> +
> + addr = mmap(NULL, sz * hpage_size,
> + PROT_READ | PROT_WRITE,
> + MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB,
> + -1, 0);
> +
> + if (addr == MAP_FAILED) {
> + if (errno == ENOMEM) {
> + tst_brkm(TCONF, cleanup,
> + "Cannot allocate hugepage, memory too fragmented?");
> + }
> +
> + tst_brkm(TBROK | TERRNO, cleanup, "Cannot allocate hugepage");
> + }
> +
> + for (i = 0; i < ARSZ; ++i, --sz) {
> + mmap_sz[i].sz = sz;
> + mmap_sz[i].addr = addr;
> +
> + TEST(pthread_create(&tid[i], NULL, thr, &mmap_sz[i]));
> + if (TEST_RETURN)
> + tst_brkm(TBROK | TRERRNO, cleanup,
> + "pthread_create failed");
> +
> + new_addr = mmap(addr, (sz - 1) * hpage_size,
> + PROT_READ | PROT_WRITE,
> + MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_FIXED,
> + -1, 0);
> +
> + if (new_addr == MAP_FAILED)
> + tst_brkm(TFAIL | TERRNO, cleanup, "mmap failed");
> +
> + addr = new_addr;
> + }
> +
> + for (i = 0; i < ARSZ; ++i) {
> + TEST(pthread_join(tid[i], NULL));
> + if (TEST_RETURN)
> + tst_brkm(TBROK | TRERRNO, cleanup,
> + "pthread_join failed");
> + }
> +
> + if (munmap(addr, sz * hpage_size) == -1)
> + tst_brkm(TFAIL | TERRNO, cleanup, "huge munmap failed");
> +}
> +
> +int main(int ac, char **av)
> +{
> + int lc, i;
> +
> + tst_parse_opts(ac, av, NULL, NULL);
> +
> + setup();
> +
> + for (lc = 0; TEST_LOOPING(lc); lc++) {
> + tst_count = 0;
> +
> + for (i = 0; i < TST_TOTAL; i++)
> + do_mmap();
> +
> + tst_resm(TPASS, "No regression found.");
> + }
> +
> + cleanup();
> + tst_exit();
> +}
>
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