- Linux-kselftest-mirror - lists.linaro.org

[PATCH v4] selftest: mm: Test if hugepage does not get leaked during __bio_release_pages()

by Donet Tom

Commit 1b151e2435fc ("block: Remove special-casing of compound pages") caused a change in behaviour when releasing the pages if the buffer does not start at the beginning of the page. This was because the calculation of the number of pages to release was incorrect. This was fixed by commit 38b43539d64b ("block: Fix page refcounts for unaligned buffers in __bio_release_pages()"). We pin the user buffer during direct I/O writes. If this buffer is a hugepage, bio_release_page() will unpin it and decrement all references and pin counts at ->bi_end_io. However, if any references to the hugepage remain post-I/O, the hugepage will not be freed upon unmap, leading to a memory leak. This patch verifies that a hugepage, used as a user buffer for DIO operations, is correctly freed upon unmapping, regardless of whether the offsets are aligned or unaligned w.r.t page boundary. Test Result Fail Scenario (Without the fix) -------------------------------------------------------- []# ./hugetlb_dio TAP version 13 1..4 No. Free pages before allocation : 7 No. Free pages after munmap : 7 ok 1 : Huge pages freed successfully ! No. Free pages before allocation : 7 No. Free pages after munmap : 7 ok 2 : Huge pages freed successfully ! No. Free pages before allocation : 7 No. Free pages after munmap : 7 ok 3 : Huge pages freed successfully ! No. Free pages before allocation : 7 No. Free pages after munmap : 6 not ok 4 : Huge pages not freed! Totals: pass:3 fail:1 xfail:0 xpass:0 skip:0 error:0 Test Result PASS Scenario (With the fix) --------------------------------------------------------- []#./hugetlb_dio TAP version 13 1..4 No. Free pages before allocation : 7 No. Free pages after munmap : 7 ok 1 : Huge pages freed successfully ! No. Free pages before allocation : 7 No. Free pages after munmap : 7 ok 2 : Huge pages freed successfully ! No. Free pages before allocation : 7 No. Free pages after munmap : 7 ok 3 : Huge pages freed successfully ! No. Free pages before allocation : 7 No. Free pages after munmap : 7 ok 4 : Huge pages freed successfully ! Totals: pass:4 fail:0 xfail:0 xpass:0 skip:0 error:0 V4: - Added this test to run_vmtests.sh. V3: - Fixed the build error when it is compiled with _FORTIFY_SOURCE. V2: - Addressed all review commets from Muhammad Usama Anjum https://lore.kernel.org/all/20240604132801.23377-1-donettom@linux.ibm.com/ V1: https://lore.kernel.org/all/20240523063905.3173-1-donettom@linux.ibm.com/#t Signed-off-by: Donet Tom <donettom(a)linux.ibm.com> Co-developed-by: Ritesh Harjani (IBM) <ritesh.list(a)gmail.com> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list(a)gmail.com> Reviewed-by: Muhammad Usama Anjum <usama.anjum(a)collabora.com> --- tools/testing/selftests/mm/Makefile | 1 + tools/testing/selftests/mm/hugetlb_dio.c | 118 ++++++++++++++++++++++ tools/testing/selftests/mm/run_vmtests.sh | 1 + 3 files changed, 120 insertions(+) create mode 100644 tools/testing/selftests/mm/hugetlb_dio.c diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile index 3b49bc3d0a3b..a1748a4c7df1 100644 --- a/tools/testing/selftests/mm/Makefile +++ b/tools/testing/selftests/mm/Makefile @@ -73,6 +73,7 @@ TEST_GEN_FILES += ksm_functional_tests TEST_GEN_FILES += mdwe_test TEST_GEN_FILES += hugetlb_fault_after_madv TEST_GEN_FILES += hugetlb_madv_vs_map +TEST_GEN_FILES += hugetlb_dio ifneq ($(ARCH),arm64) TEST_GEN_FILES += soft-dirty diff --git a/tools/testing/selftests/mm/hugetlb_dio.c b/tools/testing/selftests/mm/hugetlb_dio.c new file mode 100644 index 000000000000..986f3b6c7f7b --- /dev/null +++ b/tools/testing/selftests/mm/hugetlb_dio.c @@ -0,0 +1,118 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * This program tests for hugepage leaks after DIO writes to a file using a + * hugepage as the user buffer. During DIO, the user buffer is pinned and + * should be properly unpinned upon completion. This patch verifies that the + * kernel correctly unpins the buffer at DIO completion for both aligned and + * unaligned user buffer offsets (w.r.t page boundary), ensuring the hugepage + * is freed upon unmapping. + */ + +#define _GNU_SOURCE +#include <stdio.h> +#include <sys/stat.h> +#include <stdlib.h> +#include <fcntl.h> +#include <stdint.h> +#include <unistd.h> +#include <string.h> +#include <sys/mman.h> +#include "vm_util.h" +#include "../kselftest.h" + +void run_dio_using_hugetlb(unsigned int start_off, unsigned int end_off) +{ + int fd; + char *buffer = NULL; + char *orig_buffer = NULL; + size_t h_pagesize = 0; + size_t writesize; + int free_hpage_b = 0; + int free_hpage_a = 0; + const int mmap_flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB; + const int mmap_prot = PROT_READ | PROT_WRITE; + + writesize = end_off - start_off; + + /* Get the default huge page size */ + h_pagesize = default_huge_page_size(); + if (!h_pagesize) + ksft_exit_fail_msg("Unable to determine huge page size\n"); + + /* Open the file to DIO */ + fd = open("/tmp", O_TMPFILE | O_RDWR | O_DIRECT, 0664); + if (fd < 0) + ksft_exit_fail_perror("Error opening file\n"); + + /* Get the free huge pages before allocation */ + free_hpage_b = get_free_hugepages(); + if (free_hpage_b == 0) { + close(fd); + ksft_exit_skip("No free hugepage, exiting!\n"); + } + + /* Allocate a hugetlb page */ + orig_buffer = mmap(NULL, h_pagesize, mmap_prot, mmap_flags, -1, 0); + if (orig_buffer == MAP_FAILED) { + close(fd); + ksft_exit_fail_perror("Error mapping memory\n"); + } + buffer = orig_buffer; + buffer += start_off; + + memset(buffer, 'A', writesize); + + /* Write the buffer to the file */ + if (write(fd, buffer, writesize) != (writesize)) { + munmap(orig_buffer, h_pagesize); + close(fd); + ksft_exit_fail_perror("Error writing to file\n"); + } + + /* unmap the huge page */ + munmap(orig_buffer, h_pagesize); + close(fd); + + /* Get the free huge pages after unmap*/ + free_hpage_a = get_free_hugepages(); + + /* + * If the no. of free hugepages before allocation and after unmap does + * not match - that means there could still be a page which is pinned. + */ + if (free_hpage_a != free_hpage_b) { + ksft_print_msg("No. Free pages before allocation : %d\n", free_hpage_b); + ksft_print_msg("No. Free pages after munmap : %d\n", free_hpage_a); + ksft_test_result_fail(": Huge pages not freed!\n"); + } else { + ksft_print_msg("No. Free pages before allocation : %d\n", free_hpage_b); + ksft_print_msg("No. Free pages after munmap : %d\n", free_hpage_a); + ksft_test_result_pass(": Huge pages freed successfully !\n"); + } +} + +int main(void) +{ + size_t pagesize = 0; + + ksft_print_header(); + ksft_set_plan(4); + + /* Get base page size */ + pagesize = psize(); + + /* start and end is aligned to pagesize */ + run_dio_using_hugetlb(0, (pagesize * 3)); + + /* start is aligned but end is not aligned */ + run_dio_using_hugetlb(0, (pagesize * 3) - (pagesize / 2)); + + /* start is unaligned and end is aligned */ + run_dio_using_hugetlb(pagesize / 2, (pagesize * 3)); + + /* both start and end are unaligned */ + run_dio_using_hugetlb(pagesize / 2, (pagesize * 3) + (pagesize / 2)); + + ksft_finished(); +} + diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh index 3157204b9047..5698d519170d 100755 --- a/tools/testing/selftests/mm/run_vmtests.sh +++ b/tools/testing/selftests/mm/run_vmtests.sh @@ -265,6 +265,7 @@ CATEGORY="hugetlb" run_test ./map_hugetlb CATEGORY="hugetlb" run_test ./hugepage-mremap CATEGORY="hugetlb" run_test ./hugepage-vmemmap CATEGORY="hugetlb" run_test ./hugetlb-madvise +CATEGORY="hugetlb" run_test ./hugetlb_dio nr_hugepages_tmp=$(cat /proc/sys/vm/nr_hugepages) # For this test, we need one and just one huge page -- 2.43.0

1 year, 6 months

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[PATCH] tools/testing/selftests/x86: add dlclose function in the vdso_restorer.c

by liujing

in the main function of vdso_restorer.c,there is a dlopen function, but there is no dlclose function to close the file Signed-off-by: liujing <liujing(a)cmss.chinamobile.com> --- tools/testing/selftests/x86/vdso_restorer.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/tools/testing/selftests/x86/vdso_restorer.c b/tools/testing/selftests/x86/vdso_restorer.c index fe99f2434155..a0b1155dee31 100644 --- a/tools/testing/selftests/x86/vdso_restorer.c +++ b/tools/testing/selftests/x86/vdso_restorer.c @@ -57,6 +57,8 @@ int main() return 0; } + dlclose(vdso); + memset(&sa, 0, sizeof(sa)); sa.handler = handler_with_siginfo; sa.flags = SA_SIGINFO; -- 2.18.2

1 year, 6 months

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[PATCH 0/4] kselftests: vdso: conform tests to TAP output

by Muhammad Usama Anjum

Conform individual tests to TAP output. One patch conform one test. With this series, all vDSO tests become TAP conformant. Muhammad Usama Anjum (4): kselftests: vdso: vdso_test_clock_getres: conform test to TAP output kselftests: vdso: vdso_test_correctness: conform test to TAP output kselftests: vdso: vdso_test_getcpu: conform test to TAP output kselftests: vdso: vdso_test_gettimeofday: conform test to TAP output .../selftests/vDSO/vdso_test_clock_getres.c | 68 ++++---- .../selftests/vDSO/vdso_test_correctness.c | 146 +++++++++--------- .../testing/selftests/vDSO/vdso_test_getcpu.c | 16 +- .../selftests/vDSO/vdso_test_gettimeofday.c | 23 +-- 4 files changed, 126 insertions(+), 127 deletions(-) -- 2.39.2

1 year, 6 months

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kselftest/next kselftest-lkdtm: 3 runs, 1 regressions (v6.10-rc1-1-ga567885b1ecc9)

by kernelci.org bot

kselftest/next kselftest-lkdtm: 3 runs, 1 regressions (v6.10-rc1-1-ga567885b1ecc9) Regressions Summary ------------------- platform | arch | lab | compiler | defconfig | regressions ----------------+------+---------------+----------+------------------------------+------------ imx6q-sabrelite | arm | lab-collabora | gcc-10 | multi_v7_defconfig+kselftest | 1 Details: https://kernelci.org/test/job/kselftest/branch/next/kernel/v6.10-rc1-1-ga56… Test: kselftest-lkdtm Tree: kselftest Branch: next Describe: v6.10-rc1-1-ga567885b1ecc9 URL: https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git SHA: a567885b1ecc9ce739d128c9f2e5ef6369dfa59f Test Regressions ---------------- platform | arch | lab | compiler | defconfig | regressions ----------------+------+---------------+----------+------------------------------+------------ imx6q-sabrelite | arm | lab-collabora | gcc-10 | multi_v7_defconfig+kselftest | 1 Details: https://kernelci.org/test/plan/id/66635a06f3b94671bb7e706d Results: 62 PASS, 4 FAIL, 21 SKIP Full config: multi_v7_defconfig+kselftest Compiler: gcc-10 (arm-linux-gnueabihf-gcc (Debian 10.2.1-6) 10.2.1 20210110) Plain log: https://storage.kernelci.org//kselftest/next/v6.10-rc1-1-ga567885b1ecc9/arm… HTML log: https://storage.kernelci.org//kselftest/next/v6.10-rc1-1-ga567885b1ecc9/arm… Rootfs: http://storage.kernelci.org/images/rootfs/debian/bookworm-kselftest/2024031… * kselftest-lkdtm.lkdtm_FORTIFY_STR_OBJECT_sh: https://kernelci.org/test/case/id/66635a06f3b94671bb7e7074 new failure (last pass: v6.10-rc1)

1 year, 6 months

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kselftest/next kselftest-livepatch: 1 runs, 1 regressions (v6.10-rc1-1-ga567885b1ecc9)

by kernelci.org bot

kselftest/next kselftest-livepatch: 1 runs, 1 regressions (v6.10-rc1-1-ga567885b1ecc9) Regressions Summary ------------------- platform | arch | lab | compiler | defconfig | regressions ----------------+------+---------------+----------+------------------------------+------------ imx6q-sabrelite | arm | lab-collabora | gcc-10 | multi_v7_defconfig+kselftest | 1 Details: https://kernelci.org/test/job/kselftest/branch/next/kernel/v6.10-rc1-1-ga56… Test: kselftest-livepatch Tree: kselftest Branch: next Describe: v6.10-rc1-1-ga567885b1ecc9 URL: https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git SHA: a567885b1ecc9ce739d128c9f2e5ef6369dfa59f Test Regressions ---------------- platform | arch | lab | compiler | defconfig | regressions ----------------+------+---------------+----------+------------------------------+------------ imx6q-sabrelite | arm | lab-collabora | gcc-10 | multi_v7_defconfig+kselftest | 1 Details: https://kernelci.org/test/plan/id/6663593081d789a9147e706d Results: 1 PASS, 1 FAIL, 0 SKIP Full config: multi_v7_defconfig+kselftest Compiler: gcc-10 (arm-linux-gnueabihf-gcc (Debian 10.2.1-6) 10.2.1 20210110) Plain log: https://storage.kernelci.org//kselftest/next/v6.10-rc1-1-ga567885b1ecc9/arm… HTML log: https://storage.kernelci.org//kselftest/next/v6.10-rc1-1-ga567885b1ecc9/arm… Rootfs: http://storage.kernelci.org/images/rootfs/debian/bookworm-kselftest/2024031… * kselftest-livepatch.shardfile-livepatch: https://kernelci.org/test/case/id/6663593081d789a9147e706f failing since 114 days (last pass: v6.8-rc1, first fail: v6.8-rc1-32-g345e8abe4c355) 2024-06-07T19:01:34.236592 / # 2024-06-07T19:01:34.246478 2024-06-07T19:01:39.388006 / # export NFS_ROOTFS='/var/lib/lava/dispatcher/tmp/14231762/extract-nfsrootfs-l_zdvy_4' 2024-06-07T19:01:39.403610 export NFS_ROOTFS='/var/lib/lava/dispatcher/tmp/14231762/extract-nfsrootfs-l_zdvy_4' 2024-06-07T19:01:41.629437 / # export NFS_SERVER_IP='192.168.201.1' 2024-06-07T19:01:41.640271 export NFS_SERVER_IP='192.168.201.1' 2024-06-07T19:01:41.758009 / # # 2024-06-07T19:01:41.766397 # 2024-06-07T19:01:41.883893 / # export SHELL=/bin/bash 2024-06-07T19:01:41.894084 export SHELL=/bin/bash ... (87 line(s) more)

1 year, 6 months

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[PATCH v2 0/2] selftests/lib.mk: LLVM=1, CC=clang, and warnings

by John Hubbard

The kselftests may be built in a couple different ways: make LLVM=1 make CC=clang In order to handle both cases, set LLVM=1 if CC=clang. That way,the rest of lib.mk, and any Makefiles that include lib.mk, can base decisions solely on whether or not LLVM is set. Then, build upon that to disable a pair of clang warnings that are already silenced on gcc. Doing it this way is much better than the piecemeal approach that I started with in [1] and [2]. Thanks to Nathan Chancellor for the patch reviews that led to this approach. Changes since the first version: 1) Wrote a detailed explanation for suppressing two clang warnings, in both a lib.mk comment, and the commit description. 2) Added a Reviewed-by tag to the first patch. [1] https://lore.kernel.org/20240527214704.300444-1-jhubbard@nvidia.com [2] https://lore.kernel.org/20240527213641.299458-1-jhubbard@nvidia.com John Hubbard (2): selftests/lib.mk: handle both LLVM=1 and CC=clang builds selftests/lib.mk: silence some clang warnings that gcc already ignores tools/testing/selftests/lib.mk | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) base-commit: e0cce98fe279b64f4a7d81b7f5c3a23d80b92fbc -- 2.45.1

1 year, 6 months

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kselftest/next build: 5 builds: 0 failed, 5 passed, 1 warning (v6.10-rc1-1-ga567885b1ecc9)

by kernelci.org bot

kselftest/next build: 5 builds: 0 failed, 5 passed, 1 warning (v6.10-rc1-1-ga567885b1ecc9) Full Build Summary: https://kernelci.org/build/kselftest/branch/next/kernel/v6.10-rc1-1-ga56788… Tree: kselftest Branch: next Git Describe: v6.10-rc1-1-ga567885b1ecc9 Git Commit: a567885b1ecc9ce739d128c9f2e5ef6369dfa59f Git URL: https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git Built: 4 unique architectures Warnings Detected: arm64: arm: i386: x86_64: x86_64_defconfig+kselftest (clang-16): 1 warning Warnings summary: 1 vmlinux.o: warning: objtool: set_ftrace_ops_ro+0x39: relocation to !ENDBR: .text+0x14cf94 ================================================================================ Detailed per-defconfig build reports: -------------------------------------------------------------------------------- defconfig+kselftest (arm64, gcc-10) — PASS, 0 errors, 0 warnings, 0 section mismatches -------------------------------------------------------------------------------- i386_defconfig+kselftest (i386, gcc-10) — PASS, 0 errors, 0 warnings, 0 section mismatches -------------------------------------------------------------------------------- multi_v7_defconfig+kselftest (arm, gcc-10) — PASS, 0 errors, 0 warnings, 0 section mismatches -------------------------------------------------------------------------------- x86_64_defconfig+kselftest (x86_64, clang-16) — PASS, 0 errors, 1 warning, 0 section mismatches Warnings: vmlinux.o: warning: objtool: set_ftrace_ops_ro+0x39: relocation to !ENDBR: .text+0x14cf94 -------------------------------------------------------------------------------- x86_64_defconfig+kselftest (x86_64, gcc-10) — PASS, 0 errors, 0 warnings, 0 section mismatches --- For more info write to <info(a)kernelci.org>

1 year, 6 months

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[PATCH v3] selftest: mm: Test if hugepage does not get leaked during __bio_release_pages()

by Donet Tom

Commit 1b151e2435fc ("block: Remove special-casing of compound pages") caused a change in behaviour when releasing the pages if the buffer does not start at the beginning of the page. This was because the calculation of the number of pages to release was incorrect. This was fixed by commit 38b43539d64b ("block: Fix page refcounts for unaligned buffers in __bio_release_pages()"). We pin the user buffer during direct I/O writes. If this buffer is a hugepage, bio_release_page() will unpin it and decrement all references and pin counts at ->bi_end_io. However, if any references to the hugepage remain post-I/O, the hugepage will not be freed upon unmap, leading to a memory leak. This patch verifies that a hugepage, used as a user buffer for DIO operations, is correctly freed upon unmapping, regardless of whether the offsets are aligned or unaligned w.r.t page boundary. Test Result Fail Scenario (Without the fix) -------------------------------------------------------- []# ./hugetlb_dio TAP version 13 1..4 No. Free pages before allocation : 7 No. Free pages after munmap : 7 ok 1 : Huge pages freed successfully ! No. Free pages before allocation : 7 No. Free pages after munmap : 7 ok 2 : Huge pages freed successfully ! No. Free pages before allocation : 7 No. Free pages after munmap : 7 ok 3 : Huge pages freed successfully ! No. Free pages before allocation : 7 No. Free pages after munmap : 6 not ok 4 : Huge pages not freed! Totals: pass:3 fail:1 xfail:0 xpass:0 skip:0 error:0 Test Result PASS Scenario (With the fix) --------------------------------------------------------- []#./hugetlb_dio TAP version 13 1..4 No. Free pages before allocation : 7 No. Free pages after munmap : 7 ok 1 : Huge pages freed successfully ! No. Free pages before allocation : 7 No. Free pages after munmap : 7 ok 2 : Huge pages freed successfully ! No. Free pages before allocation : 7 No. Free pages after munmap : 7 ok 3 : Huge pages freed successfully ! No. Free pages before allocation : 7 No. Free pages after munmap : 7 ok 4 : Huge pages freed successfully ! Totals: pass:4 fail:0 xfail:0 xpass:0 skip:0 error:0 V3: - Fixed the build error when it is compiled with _FORTIFY_SOURCE. V2: - Addressed all review commets from Muhammad Usama Anjum https://lore.kernel.org/all/20240604132801.23377-1-donettom@linux.ibm.com/ V1: https://lore.kernel.org/all/20240523063905.3173-1-donettom@linux.ibm.com/#t Signed-off-by: Donet Tom <donettom(a)linux.ibm.com> Co-developed-by: Ritesh Harjani (IBM) <ritesh.list(a)gmail.com> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list(a)gmail.com> --- tools/testing/selftests/mm/Makefile | 1 + tools/testing/selftests/mm/hugetlb_dio.c | 118 +++++++++++++++++++++++ 2 files changed, 119 insertions(+) create mode 100644 tools/testing/selftests/mm/hugetlb_dio.c diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile index 3b49bc3d0a3b..a1748a4c7df1 100644 --- a/tools/testing/selftests/mm/Makefile +++ b/tools/testing/selftests/mm/Makefile @@ -73,6 +73,7 @@ TEST_GEN_FILES += ksm_functional_tests TEST_GEN_FILES += mdwe_test TEST_GEN_FILES += hugetlb_fault_after_madv TEST_GEN_FILES += hugetlb_madv_vs_map +TEST_GEN_FILES += hugetlb_dio ifneq ($(ARCH),arm64) TEST_GEN_FILES += soft-dirty diff --git a/tools/testing/selftests/mm/hugetlb_dio.c b/tools/testing/selftests/mm/hugetlb_dio.c new file mode 100644 index 000000000000..986f3b6c7f7b --- /dev/null +++ b/tools/testing/selftests/mm/hugetlb_dio.c @@ -0,0 +1,118 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * This program tests for hugepage leaks after DIO writes to a file using a + * hugepage as the user buffer. During DIO, the user buffer is pinned and + * should be properly unpinned upon completion. This patch verifies that the + * kernel correctly unpins the buffer at DIO completion for both aligned and + * unaligned user buffer offsets (w.r.t page boundary), ensuring the hugepage + * is freed upon unmapping. + */ + +#define _GNU_SOURCE +#include <stdio.h> +#include <sys/stat.h> +#include <stdlib.h> +#include <fcntl.h> +#include <stdint.h> +#include <unistd.h> +#include <string.h> +#include <sys/mman.h> +#include "vm_util.h" +#include "../kselftest.h" + +void run_dio_using_hugetlb(unsigned int start_off, unsigned int end_off) +{ + int fd; + char *buffer = NULL; + char *orig_buffer = NULL; + size_t h_pagesize = 0; + size_t writesize; + int free_hpage_b = 0; + int free_hpage_a = 0; + const int mmap_flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB; + const int mmap_prot = PROT_READ | PROT_WRITE; + + writesize = end_off - start_off; + + /* Get the default huge page size */ + h_pagesize = default_huge_page_size(); + if (!h_pagesize) + ksft_exit_fail_msg("Unable to determine huge page size\n"); + + /* Open the file to DIO */ + fd = open("/tmp", O_TMPFILE | O_RDWR | O_DIRECT, 0664); + if (fd < 0) + ksft_exit_fail_perror("Error opening file\n"); + + /* Get the free huge pages before allocation */ + free_hpage_b = get_free_hugepages(); + if (free_hpage_b == 0) { + close(fd); + ksft_exit_skip("No free hugepage, exiting!\n"); + } + + /* Allocate a hugetlb page */ + orig_buffer = mmap(NULL, h_pagesize, mmap_prot, mmap_flags, -1, 0); + if (orig_buffer == MAP_FAILED) { + close(fd); + ksft_exit_fail_perror("Error mapping memory\n"); + } + buffer = orig_buffer; + buffer += start_off; + + memset(buffer, 'A', writesize); + + /* Write the buffer to the file */ + if (write(fd, buffer, writesize) != (writesize)) { + munmap(orig_buffer, h_pagesize); + close(fd); + ksft_exit_fail_perror("Error writing to file\n"); + } + + /* unmap the huge page */ + munmap(orig_buffer, h_pagesize); + close(fd); + + /* Get the free huge pages after unmap*/ + free_hpage_a = get_free_hugepages(); + + /* + * If the no. of free hugepages before allocation and after unmap does + * not match - that means there could still be a page which is pinned. + */ + if (free_hpage_a != free_hpage_b) { + ksft_print_msg("No. Free pages before allocation : %d\n", free_hpage_b); + ksft_print_msg("No. Free pages after munmap : %d\n", free_hpage_a); + ksft_test_result_fail(": Huge pages not freed!\n"); + } else { + ksft_print_msg("No. Free pages before allocation : %d\n", free_hpage_b); + ksft_print_msg("No. Free pages after munmap : %d\n", free_hpage_a); + ksft_test_result_pass(": Huge pages freed successfully !\n"); + } +} + +int main(void) +{ + size_t pagesize = 0; + + ksft_print_header(); + ksft_set_plan(4); + + /* Get base page size */ + pagesize = psize(); + + /* start and end is aligned to pagesize */ + run_dio_using_hugetlb(0, (pagesize * 3)); + + /* start is aligned but end is not aligned */ + run_dio_using_hugetlb(0, (pagesize * 3) - (pagesize / 2)); + + /* start is unaligned and end is aligned */ + run_dio_using_hugetlb(pagesize / 2, (pagesize * 3)); + + /* both start and end are unaligned */ + run_dio_using_hugetlb(pagesize / 2, (pagesize * 3) + (pagesize / 2)); + + ksft_finished(); +} + -- 2.43.0

1 year, 6 months

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[PATCH v2 0/2] memfd: fix MFD_NOEXEC_SEAL to be non-sealable

by jeffxu＠chromium.org

From: Jeff Xu <jeffxu(a)google.com> By default, memfd_create() creates a non-sealable MFD, unless the MFD_ALLOW_SEALING flag is set. When the MFD_NOEXEC_SEAL flag is initially introduced, the MFD created with that flag is sealable, even though MFD_ALLOW_SEALING is not set. This patch changes MFD_NOEXEC_SEAL to be non-sealable by default, unless MFD_ALLOW_SEALING is explicitly set. This is a non-backward compatible change. However, as MFD_NOEXEC_SEAL is new, we expect not many applications will rely on the nature of MFD_NOEXEC_SEAL being sealable. In most cases, the application already sets MFD_ALLOW_SEALING if they need a sealable MFD. Additionally, this enhances the useability of pid namespace sysctl vm.memfd_noexec. When vm.memfd_noexec equals 1 or 2, the kernel will add MFD_NOEXEC_SEAL if mfd_create does not specify MFD_EXEC or MFD_NOEXEC_SEAL, and the addition of MFD_NOEXEC_SEAL enables the MFD to be sealable. This means, any application that does not desire this behavior will be unable to utilize vm.memfd_noexec = 1 or 2 to migrate/enforce non-executable MFD. This adjustment ensures that applications can anticipate that the sealable characteristic will remain unmodified by vm.memfd_noexec. This patch was initially developed by Barnabás Pőcze, and Barnabás used Debian Code Search and GitHub to try to find potential breakages and could only find a single one. Dbus-broker's memfd_create() wrapper is aware of this implicit `MFD_ALLOW_SEALING` behavior, and tries to work around it [1]. This workaround will break. Luckily, this only affects the test suite, it does not affect the normal operations of dbus-broker. There is a PR with a fix[2]. In addition, David Rheinsberg also raised similar fix in [3] [1]: https://github.com/bus1/dbus-broker/blob/9eb0b7e5826fc76cad7b025bc46f267d4a… [2]: https://github.com/bus1/dbus-broker/pull/366 [3]: https://lore.kernel.org/lkml/20230714114753.170814-1-david@readahead.eu/ History ====== V2: update commit message. add testcase for vm.memfd_noexec add documentation. V1: https://lore.kernel.org/lkml/20240513191544.94754-1-pobrn@protonmail.com/ Jeff Xu (2): memfd: fix MFD_NOEXEC_SEAL to be non-sealable by default memfd:add MEMFD_NOEXEC_SEAL documentation Documentation/userspace-api/index.rst | 1 + Documentation/userspace-api/mfd_noexec.rst | 90 ++++++++++++++++++++++ mm/memfd.c | 9 +-- tools/testing/selftests/memfd/memfd_test.c | 26 ++++++- 4 files changed, 120 insertions(+), 6 deletions(-) create mode 100644 Documentation/userspace-api/mfd_noexec.rst -- 2.45.1.288.g0e0cd299f1-goog

1 year, 6 months

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[PATCH v1] memfd: `MFD_NOEXEC_SEAL` should not imply `MFD_ALLOW_SEALING`

by Barnabás Pőcze

`MFD_NOEXEC_SEAL` should remove the executable bits and set `F_SEAL_EXEC` to prevent further modifications to the executable bits as per the comment in the uapi header file: not executable and sealed to prevent changing to executable However, currently, it also unsets `F_SEAL_SEAL`, essentially acting as a superset of `MFD_ALLOW_SEALING`. Nothing implies that it should be so, and indeed up until the second version of the of the patchset[0] that introduced `MFD_EXEC` and `MFD_NOEXEC_SEAL`, `F_SEAL_SEAL` was not removed, however it was changed in the third revision of the patchset[1] without a clear explanation. This behaviour is suprising for application developers, there is no documentation that would reveal that `MFD_NOEXEC_SEAL` has the additional effect of `MFD_ALLOW_SEALING`. So do not remove `F_SEAL_SEAL` when `MFD_NOEXEC_SEAL` is requested. This is technically an ABI break, but it seems very unlikely that an application would depend on this behaviour (unless by accident). [0]: https://lore.kernel.org/lkml/20220805222126.142525-3-jeffxu@google.com/ [1]: https://lore.kernel.org/lkml/20221202013404.163143-3-jeffxu@google.com/ Fixes: 105ff5339f498a ("mm/memfd: add MFD_NOEXEC_SEAL and MFD_EXEC") Signed-off-by: Barnabás Pőcze <pobrn(a)protonmail.com> --- Or did I miss the explanation as to why MFD_NOEXEC_SEAL should imply MFD_ALLOW_SEALING? If so, please direct me to it and sorry for the noise. --- mm/memfd.c | 9 ++++----- tools/testing/selftests/memfd/memfd_test.c | 2 +- 2 files changed, 5 insertions(+), 6 deletions(-) diff --git a/mm/memfd.c b/mm/memfd.c index 7d8d3ab3fa37..8b7f6afee21d 100644 --- a/mm/memfd.c +++ b/mm/memfd.c @@ -356,12 +356,11 @@ SYSCALL_DEFINE2(memfd_create, inode->i_mode &= ~0111; file_seals = memfd_file_seals_ptr(file); - if (file_seals) { - *file_seals &= ~F_SEAL_SEAL; + if (file_seals) *file_seals |= F_SEAL_EXEC; - } - } else if (flags & MFD_ALLOW_SEALING) { - /* MFD_EXEC and MFD_ALLOW_SEALING are set */ + } + + if (flags & MFD_ALLOW_SEALING) { file_seals = memfd_file_seals_ptr(file); if (file_seals) *file_seals &= ~F_SEAL_SEAL; diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c index 18f585684e20..b6a7ad68c3c1 100644 --- a/tools/testing/selftests/memfd/memfd_test.c +++ b/tools/testing/selftests/memfd/memfd_test.c @@ -1151,7 +1151,7 @@ static void test_noexec_seal(void) mfd_def_size, MFD_CLOEXEC | MFD_NOEXEC_SEAL); mfd_assert_mode(fd, 0666); - mfd_assert_has_seals(fd, F_SEAL_EXEC); + mfd_assert_has_seals(fd, F_SEAL_SEAL | F_SEAL_EXEC); mfd_fail_chmod(fd, 0777); close(fd); } -- 2.45.0

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