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

[PATCH] tools/nolibc: ensure fast64 integer types have 64 bits

by Thomas Weißschuh

On 32bit platforms size_t is not enough to represent [u]int_fast64_t. Fixes: 3e9fd4e9a1d5 ("tools/nolibc: add integer types and integer limit macros") Signed-off-by: Thomas Weißschuh <linux(a)weissschuh.net> --- Cc: Vincent Dagonneau <v(a)vda.io> Note: We could also fall back to compiler-provided data like: __UINT_FAST{8,16,32,64}_{TYPE,MIN,MAX}__ --- tools/include/nolibc/stdint.h | 4 ++-- tools/testing/selftests/nolibc/nolibc-test.c | 6 +++--- 2 files changed, 5 insertions(+), 5 deletions(-) diff --git a/tools/include/nolibc/stdint.h b/tools/include/nolibc/stdint.h index c1ce4f5e0603..3fc418cfc3d7 100644 --- a/tools/include/nolibc/stdint.h +++ b/tools/include/nolibc/stdint.h @@ -36,8 +36,8 @@ typedef ssize_t int_fast16_t; typedef size_t uint_fast16_t; typedef ssize_t int_fast32_t; typedef size_t uint_fast32_t; -typedef ssize_t int_fast64_t; -typedef size_t uint_fast64_t; +typedef int64_t int_fast64_t; +typedef uint64_t uint_fast64_t; typedef int64_t intmax_t; typedef uint64_t uintmax_t; diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c index 7de46305f419..65be0317d184 100644 --- a/tools/testing/selftests/nolibc/nolibc-test.c +++ b/tools/testing/selftests/nolibc/nolibc-test.c @@ -696,9 +696,9 @@ int run_stdlib(int min, int max) CASE_TEST(limit_int_fast32_min); EXPECT_EQ(1, INT_FAST32_MIN, (int_fast32_t) INTPTR_MIN); break; CASE_TEST(limit_int_fast32_max); EXPECT_EQ(1, INT_FAST32_MAX, (int_fast32_t) INTPTR_MAX); break; CASE_TEST(limit_uint_fast32_max); EXPECT_EQ(1, UINT_FAST32_MAX, (uint_fast32_t) UINTPTR_MAX); break; - CASE_TEST(limit_int_fast64_min); EXPECT_EQ(1, INT_FAST64_MIN, (int_fast64_t) INTPTR_MIN); break; - CASE_TEST(limit_int_fast64_max); EXPECT_EQ(1, INT_FAST64_MAX, (int_fast64_t) INTPTR_MAX); break; - CASE_TEST(limit_uint_fast64_max); EXPECT_EQ(1, UINT_FAST64_MAX, (uint_fast64_t) UINTPTR_MAX); break; + CASE_TEST(limit_int_fast64_min); EXPECT_EQ(1, INT_FAST64_MIN, (int_fast64_t) INT64_MIN); break; + CASE_TEST(limit_int_fast64_max); EXPECT_EQ(1, INT_FAST64_MAX, (int_fast64_t) INT64_MAX); break; + CASE_TEST(limit_uint_fast64_max); EXPECT_EQ(1, UINT_FAST64_MAX, (uint_fast64_t) UINT64_MAX); break; #if __SIZEOF_LONG__ == 8 CASE_TEST(limit_intptr_min); EXPECT_EQ(1, INTPTR_MIN, (intptr_t) 0x8000000000000000LL); break; CASE_TEST(limit_intptr_max); EXPECT_EQ(1, INTPTR_MAX, (intptr_t) 0x7fffffffffffffffLL); break; --- base-commit: 5b21219d67d3483144d10332709d0c04f733ab93 change-id: 20230530-nolibc-fast64-8777cdbc7e01 Best regards, -- Thomas Weißschuh <linux(a)weissschuh.net>

2 years, 3 months

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[PATCH] selftests/nolibc: test_fork: fix up duplicated print

by Zhangjin Wu

running nolibc-test with glibc on x86_64 got such print issue: 29 execve_root = -1 EACCES [OK] 30 fork30 fork = 0 [OK] 31 getdents64_root = 712 [OK] The fork test case has three printf calls: (1) llen += printf("%d %s", test, #name); (2) llen += printf(" = %d %s ", expr, errorname(errno)); (3) llen += pad_spc(llen, 64, "[FAIL]\n"); --> vfprintf() In the following scene, the above issue happens: (a) The parent calls (1) (b) The parent calls fork() (c) The child runs and shares the print buffer of (1) (d) The child exits, flushs the print buffer and closes its own stdout/stderr * "30 fork" is printed at the first time. (e) The parent calls (2) and (3), with "\n" in (3), it flushs the whole buffer * "30 fork = 0 ..." is printed Therefore, there are two "30 fork" in the stdout. Between (a) and (b), if flush the stdout (and the sterr), the child in stage (c) will not be able to 'see' the print buffer. Signed-off-by: Zhangjin Wu <falcon(a)tinylab.org> --- tools/testing/selftests/nolibc/nolibc-test.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c index 7de46305f419..88323a60aa4a 100644 --- a/tools/testing/selftests/nolibc/nolibc-test.c +++ b/tools/testing/selftests/nolibc/nolibc-test.c @@ -486,7 +486,13 @@ static int test_getpagesize(void) static int test_fork(void) { int status; - pid_t pid = fork(); + pid_t pid; + + /* flush the printf buffer to avoid child flush it */ + fflush(stdout); + fflush(stderr); + + pid = fork(); switch (pid) { case -1: -- 2.25.1

2 years, 3 months

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[PATCH 0/1] selftests: error out if kernel header files are not yet built

by John Hubbard

Hi, This is somewhat related to the 11-patch series that I just posted [1], but I hadn't originally planned to go this far with it. But since David Hildenbrand asked if we could warn in this case [2], here it is. It turns out that automatically doing the "make headers" correctly is much harder than just warning, so I stopped at that point. It works well, though. [1] https://lore.kernel.org/all/20230603021558.95299-1-jhubbard@nvidia.com/ [2] https://lore.kernel.org/all/a4fbc191-9acb-5db8-a375-96c0c1ba3fcd@redhat.com/ thanks, John Hubbard Cc: David Hildenbrand <david(a)redhat.com> Cc: Peter Xu <peterx(a)redhat.com> Cc: Muhammad Usama Anjum <usama.anjum(a)collabora.com> Cc: Jonathan Corbet <corbet(a)lwn.net> Cc: linux-doc(a)vger.kernel.org John Hubbard (1): selftests: error out if kernel header files are not yet built tools/testing/selftests/lib.mk | 36 +++++++++++++++++++++++++++++++--- 1 file changed, 33 insertions(+), 3 deletions(-) base-commit: e5282a7d8f6b604f2bb6a06457734b8cf1e2f8f2 -- 2.40.1

2 years, 3 months

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[PATCH] Fix gitignore for recently added usptream self tests

by Weihao Gao

This resolves the issue that generated binary is showing up as an untracked git file after every build on the kernel. Signed-off-by: Weihao Gao <weihaogao(a)google.com> --- tools/testing/selftests/net/.gitignore | 3 +++ 1 file changed, 3 insertions(+) diff --git a/tools/testing/selftests/net/.gitignore b/tools/testing/selftests/net/.gitignore index 80f06aa62034..f27a7338b60e 100644 --- a/tools/testing/selftests/net/.gitignore +++ b/tools/testing/selftests/net/.gitignore @@ -8,8 +8,10 @@ diag_uid fin_ack_lat gro hwtstamp_config +io_uring_zerocopy_tx ioam6_parser ip_defrag +ip_local_port_range ipsec ipv6_flowlabel ipv6_flowlabel_mgr @@ -26,6 +28,7 @@ reuseport_bpf_cpu reuseport_bpf_numa reuseport_dualstack rxtimestamp +sctp_hello sk_bind_sendto_listen sk_connect_zero_addr socket -- 2.41.0.rc0.172.g3f132b7071-goog

2 years, 3 months

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[PATCH] selftests/x86/amx: Add a CPU hotplug test

by Chang S. Bae

Adamos found the issue with the cached XFD state [1]. Although the XFD state is reset on the CPU hotplug, the per-CPU XFD cache is missing the reset. Then, running an AMX thread there, the staled value causes the kernel crash to kill the thread. This is reproducible when moving an AMX thread to the hot-plugged CPU. So, add a test case to ensure no issue with that. It repeats the test due to possible inconsistencies. Then, along with the hotplug cost, it will bring a noticeable runtime increase. But, the overall test has a quick turnaround time. Link: https://lore.kernel.org/lkml/20230519112315.30616-1-attofari@amazon.de/ [1] Signed-off-by: Chang S. Bae <chang.seok.bae(a)intel.com> Cc: Thomas Gleixner <tglx(a)linutronix.de> Cc: Dave Hansen <dave.hansen(a)linux.intel.com> Cc: Adamos Ttofari <attofari(a)amazon.de> Cc: Shuah Khan <shuah(a)kernel.org> Cc: linux-kselftest(a)vger.kernel.org Cc: linux-kernel(a)vger.kernel.org --- The overall x86 selftest via "$ make TARGETS='x86' kselftest" takes about 3.5 -> 5.5 seconds. 'amx_64' itself took about 1.5 more seconds over 0.x seconds. But, this overall runtime still takes in a matter of some seconds, which should be fine I thought. --- tools/testing/selftests/x86/amx.c | 133 ++++++++++++++++++++++++++++-- 1 file changed, 126 insertions(+), 7 deletions(-) diff --git a/tools/testing/selftests/x86/amx.c b/tools/testing/selftests/x86/amx.c index d884fd69dd51..6f2f0598c706 100644 --- a/tools/testing/selftests/x86/amx.c +++ b/tools/testing/selftests/x86/amx.c @@ -3,6 +3,7 @@ #define _GNU_SOURCE #include <err.h> #include <errno.h> +#include <fcntl.h> #include <pthread.h> #include <setjmp.h> #include <stdio.h> @@ -25,6 +26,8 @@ # error This test is 64-bit only #endif +#define BUF_LEN 1000 + #define XSAVE_HDR_OFFSET 512 #define XSAVE_HDR_SIZE 64 @@ -239,11 +242,10 @@ static inline uint64_t get_fpx_sw_bytes_features(void *buffer) } /* Work around printf() being unsafe in signals: */ -#define SIGNAL_BUF_LEN 1000 -char signal_message_buffer[SIGNAL_BUF_LEN]; +char signal_message_buffer[BUF_LEN]; void sig_print(char *msg) { - int left = SIGNAL_BUF_LEN - strlen(signal_message_buffer) - 1; + int left = BUF_LEN - strlen(signal_message_buffer) - 1; strncat(signal_message_buffer, msg, left); } @@ -767,15 +769,15 @@ static int create_threads(int num, struct futex_info *finfo) return 0; } -static void affinitize_cpu0(void) +static inline void affinitize_cpu(int cpu) { cpu_set_t cpuset; CPU_ZERO(&cpuset); - CPU_SET(0, &cpuset); + CPU_SET(cpu, &cpuset); if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0) - fatal_error("sched_setaffinity to CPU 0"); + fatal_error("sched_setaffinity to CPU %d", cpu); } static void test_context_switch(void) @@ -784,7 +786,7 @@ static void test_context_switch(void) int i; /* Affinitize to one CPU to force context switches */ - affinitize_cpu0(); + affinitize_cpu(0); req_xtiledata_perm(); @@ -926,6 +928,121 @@ static void test_ptrace(void) err(1, "ptrace test"); } +/* CPU Hotplug test */ + +static void __hotplug_cpu(int online, int cpu) +{ + char buf[BUF_LEN] = {}; + int fd, rc; + + strncat(buf, "/sys/devices/system/cpu/cpu", BUF_LEN); + snprintf(buf + strlen(buf), BUF_LEN - strlen(buf), "%d", cpu); + strncat(buf, "/online", BUF_LEN - strlen(buf)); + + fd = open(buf, O_RDWR); + if (fd == -1) + fatal_error("open()"); + + snprintf(buf, BUF_LEN, "%d", online); + rc = write(fd, buf, strlen(buf)); + if (rc == -1) + fatal_error("write()"); + + rc = close(fd); + if (rc == -1) + fatal_error("close()"); +} + +static void offline_cpu(int cpu) +{ + __hotplug_cpu(0, cpu); +} + +static void online_cpu(int cpu) +{ + __hotplug_cpu(1, cpu); +} + +static jmp_buf jmpbuf; + +static void handle_sigsegv(int sig, siginfo_t *si, void *ctx_void) +{ + siglongjmp(jmpbuf, 1); +} + +#define RETRY 5 + +/* + * Sanity-check the hotplug CPU for its (re-)initialization. + * + * Create an AMX thread on a CPU, while the hotplug CPU went offline. + * Then, plug the offlined back, and move the thread to run on it. + * + * Repeat this multiple times to ensure no inconsistent failure. + * If something goes wrong, the thread will get a signal or killed. + */ +static void *switch_cpus(void *arg) +{ + int *result = (int *)arg; + int i = 0; + + affinitize_cpu(0); + offline_cpu(1); + load_rand_tiledata(stashed_xsave); + + sethandler(SIGSEGV, handle_sigsegv, SA_ONSTACK); + for (i = 0; i < RETRY; i++) { + if (i > 0) { + affinitize_cpu(0); + offline_cpu(1); + } + if (sigsetjmp(jmpbuf, 1) == 0) { + online_cpu(1); + affinitize_cpu(1); + } else { + *result = 1; + goto out; + } + } + *result = 0; +out: + clearhandler(SIGSEGV); + return result; +} + +static void test_cpuhp(void) +{ + int max_cpu_num = sysconf(_SC_NPROCESSORS_ONLN) - 1; + void *thread_retval; + pthread_t thread; + int result, rc; + + if (!max_cpu_num) { + printf("[SKIP]\tThe running system has no more CPU for the hotplug test.\n"); + return; + } + + printf("[RUN]\tTest AMX use with the CPU hotplug.\n"); + + if (pthread_create(&thread, NULL, switch_cpus, &result)) + fatal_error("pthread_create()"); + + rc = pthread_join(thread, &thread_retval); + + if (rc) + fatal_error("pthread_join()"); + + /* + * Either an invalid retval or a failed result indicates + * the test failure. + */ + if (thread_retval != &result || result != 0) + printf("[FAIL]\tThe AMX thread had an issue (%s).\n", + thread_retval != &result ? "killed" : "signaled"); + else + printf("[OK]\tThe AMX thread had no issue.\n"); +} + int main(void) { /* Check hardware availability at first */ @@ -948,6 +1065,8 @@ int main(void) test_ptrace(); + test_cpuhp(); + clearhandler(SIGILL); free_stashed_xsave(); base-commit: 7877cb91f1081754a1487c144d85dc0d2e2e7fc4 -- 2.17.1

2 years, 3 months

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[PATCH 0/2] drivers: base: Add tests showing devm handling inconsistencies

by Maxime Ripard

Hi, This follows the discussion here: https://lore.kernel.org/linux-kselftest/20230324123157.bbwvfq4gsxnlnfwb@hou… This shows a couple of inconsistencies with regard to how device-managed resources are cleaned up. Basically, devm resources will only be cleaned up if the device is attached to a bus and bound to a driver. Failing any of these cases, a call to device_unregister will not end up in the devm resources being released. We had to work around it in DRM to provide helpers to create a device for kunit tests, but the current discussion around creating similar, generic, helpers for kunit resumed interest in fixing this. This can be tested using the command: ./tools/testing/kunit/kunit.py run --kunitconfig=drivers/base/test/ Let me know what you think, Maxime Signed-off-by: Maxime Ripard <maxime(a)cerno.tech> --- Maxime Ripard (2): drivers: base: Add basic devm tests for root devices drivers: base: Add basic devm tests for platform devices drivers/base/test/.kunitconfig | 2 + drivers/base/test/Kconfig | 4 + drivers/base/test/Makefile | 3 + drivers/base/test/platform-device-test.c | 278 +++++++++++++++++++++++++++++++ drivers/base/test/root-device-test.c | 120 +++++++++++++ 5 files changed, 407 insertions(+) --- base-commit: a6faf7ea9fcb7267d06116d4188947f26e00e57e change-id: 20230329-kunit-devm-inconsistencies-test-5e5a7d01e60d Best regards, -- Maxime Ripard <maxime(a)cerno.tech>

2 years, 3 months

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Wyższa konwersja w e-sklepie

by Kamil Durjasz

Dzień dobry, w jaki sposób docierają Państwo do odbiorców? Tworzymy potężne narzędzia sprzedaży, które pozwalają kompleksowo rozwiązać problemy potencjalnych klientów i skutecznie wpłynąć na ich decyzje zakupowe. Skupiamy się na Państwa potrzebach związanych z obsługą sklepu, oczekiwaniach i planach sprzedażowych. Szczegółowo dopasowujemy grafikę, funkcjonalności, strukturę i mikrointerakcje do Państwa grupy docelowej, co przekłada się na oczekiwane rezultaty. Chętnie przedstawię dotychczasowe realizacje, aby mogli Państwo przekonać się o naszych możliwościach. Mogę się skontaktować? Pozdrawiam Kamil Durjasz

2 years, 3 months

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[PATCH bpf v2 0/2] Fix elem_size not being set for inner maps

by Rhys Rustad-Elliott

Commit d937bc3449fa ("bpf: make uniform use of array->elem_size everywhere in arraymap.c") changed array_map_gen_lookup to use array->elem_size instead of round_up(map->value_size, 8) as the element size when generating code to access a value in an array map. array->elem_size, however, is not set by bpf_map_meta_alloc when initializing an BPF_MAP_TYPE_ARRAY_OF_MAPS or BPF_MAP_TYPE_HASH_OF_MAPS. This results in array_map_gen_lookup incorrectly outputting code that always accesses index 0 in the array (as the index will be calculated via a multiplication with the element size, which is incorrectly set to 0). This patchset sets elem_size on the bpf_array object when allocating an array or hash of maps to fix this and adds a selftest that accesses an array map nested within a hash of maps at a nonzero index to prevent regressions. v1: https://lore.kernel.org/bpf/95b5da7c-ee52-3ecb-0a4e-f6a7a114f269@linux.dev/ Changelog: v1 -> v2: Address comments by Martin KaFai Lau: - Directly use inner_array->elem_size instead of using round_up - Move selftests to a new patch - Use ASSERT_* macros instead of CHECK and remove duration - Remove unnecessary usleep - Shorten selftest name Rhys Rustad-Elliott (2): bpf: Fix elem_size not being set for inner maps selftests/bpf: Add access_inner_map selftest kernel/bpf/map_in_map.c | 8 +++- .../bpf/prog_tests/inner_array_lookup.c | 31 +++++++++++++ .../bpf/progs/test_inner_array_lookup.c | 45 +++++++++++++++++++ 3 files changed, 82 insertions(+), 2 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/inner_array_lookup.c create mode 100644 tools/testing/selftests/bpf/progs/test_inner_array_lookup.c -- 2.40.1

2 years, 3 months

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[PATCH] Documentation: kunit: Rename references to kunit_abort()

by David Gow

The kunit_abort() function has been renamed __kunit_abort(), update the references to it in the documentation. Suggested-by: Daniel Latypov <dlatypov(a)google.com> Signed-off-by: David Gow <davidgow(a)google.com> --- Documentation/dev-tools/kunit/architecture.rst | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/Documentation/dev-tools/kunit/architecture.rst b/Documentation/dev-tools/kunit/architecture.rst index e95ab05342bb..f335f883f8f6 100644 --- a/Documentation/dev-tools/kunit/architecture.rst +++ b/Documentation/dev-tools/kunit/architecture.rst @@ -119,9 +119,9 @@ All expectations/assertions are formatted as: terminated immediately. - Assertions call the function: - ``void __noreturn kunit_abort(struct kunit *)``. + ``void __noreturn __kunit_abort(struct kunit *)``. - - ``kunit_abort`` calls the function: + - ``__kunit_abort`` calls the function: ``void __noreturn kunit_try_catch_throw(struct kunit_try_catch *try_catch)``. - ``kunit_try_catch_throw`` calls the function: -- 2.41.0.rc2.161.g9c6817b8e7-goog

2 years, 3 months

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[PATCH v16 0/5] Implement IOCTL to get and optionally clear info about PTEs

by Muhammad Usama Anjum

*Changes in v16* - Fix a corner case - Add exclusive PM_SCAN_OP_WP back *Changes in v15* - Build fix (Add missed build fix in RESEND) *Changes in v14* - Fix build error caused by #ifdef added at last minute in some configs *Changes in v13* - Rebase on top of next-20230414 - Give-up on using uffd_wp_range() and write new helpers, flush tlb only once *Changes in v12* - Update and other memory types to UFFD_FEATURE_WP_ASYNC - Rebaase on top of next-20230406 - Review updates *Changes in v11* - Rebase on top of next-20230307 - Base patches on UFFD_FEATURE_WP_UNPOPULATED - Do a lot of cosmetic changes and review updates - Remove ENGAGE_WP + !GET operation as it can be performed with UFFDIO_WRITEPROTECT *Changes in v10* - Add specific condition to return error if hugetlb is used with wp async - Move changes in tools/include/uapi/linux/fs.h to separate patch - Add documentation *Changes in v9:* - Correct fault resolution for userfaultfd wp async - Fix build warnings and errors which were happening on some configs - Simplify pagemap ioctl's code *Changes in v8:* - Update uffd async wp implementation - Improve PAGEMAP_IOCTL implementation *Changes in v7:* - Add uffd wp async - Update the IOCTL to use uffd under the hood instead of soft-dirty flags *Motivation* The real motivation for adding PAGEMAP_SCAN IOCTL is to emulate Windows GetWriteWatch() syscall [1]. The GetWriteWatch{} retrieves the addresses of the pages that are written to in a region of virtual memory. This syscall is used in Windows applications and games etc. This syscall is being emulated in pretty slow manner in userspace. Our purpose is to enhance the kernel such that we translate it efficiently in a better way. Currently some out of tree hack patches are being used to efficiently emulate it in some kernels. We intend to replace those with these patches. So the whole gaming on Linux can effectively get benefit from this. It means there would be tons of users of this code. CRIU use case [2] was mentioned by Andrei and Danylo: > Use cases for migrating sparse VMAs are binaries sanitized with ASAN, > MSAN or TSAN [3]. All of these sanitizers produce sparse mappings of > shadow memory [4]. Being able to migrate such binaries allows to highly > reduce the amount of work needed to identify and fix post-migration > crashes, which happen constantly. Andrei's defines the following uses of this code: * it is more granular and allows us to track changed pages more effectively. The current interface can clear dirty bits for the entire process only. In addition, reading info about pages is a separate operation. It means we must freeze the process to read information about all its pages, reset dirty bits, only then we can start dumping pages. The information about pages becomes more and more outdated, while we are processing pages. The new interface solves both these downsides. First, it allows us to read pte bits and clear the soft-dirty bit atomically. It means that CRIU will not need to freeze processes to pre-dump their memory. Second, it clears soft-dirty bits for a specified region of memory. It means CRIU will have actual info about pages to the moment of dumping them. * The new interface has to be much faster because basic page filtering is happening in the kernel. With the old interface, we have to read pagemap for each page. *Implementation Evolution (Short Summary)* From the definition of GetWriteWatch(), we feel like kernel's soft-dirty feature can be used under the hood with some additions like: * reset soft-dirty flag for only a specific region of memory instead of clearing the flag for the entire process * get and clear soft-dirty flag for a specific region atomically So we decided to use ioctl on pagemap file to read or/and reset soft-dirty flag. But using soft-dirty flag, sometimes we get extra pages which weren't even written. They had become soft-dirty because of VMA merging and VM_SOFTDIRTY flag. This breaks the definition of GetWriteWatch(). We were able to by-pass this short coming by ignoring VM_SOFTDIRTY until David reported that mprotect etc messes up the soft-dirty flag while ignoring VM_SOFTDIRTY [5]. This wasn't happening until [6] got introduced. We discussed if we can revert these patches. But we could not reach to any conclusion. So at this point, I made couple of tries to solve this whole VM_SOFTDIRTY issue by correcting the soft-dirty implementation: * [7] Correct the bug fixed wrongly back in 2014. It had potential to cause regression. We left it behind. * [8] Keep a list of soft-dirty part of a VMA across splits and merges. I got the reply don't increase the size of the VMA by 8 bytes. At this point, we left soft-dirty considering it is too much delicate and userfaultfd [9] seemed like the only way forward. From there onward, we have been basing soft-dirty emulation on userfaultfd wp feature where kernel resolves the faults itself when WP_ASYNC feature is used. It was straight forward to add WP_ASYNC feature in userfautlfd. Now we get only those pages dirty or written-to which are really written in reality. (PS There is another WP_UNPOPULATED userfautfd feature is required which is needed to avoid pre-faulting memory before write-protecting [9].) All the different masks were added on the request of CRIU devs to create interface more generic and better. [1] https://learn.microsoft.com/en-us/windows/win32/api/memoryapi/nf-memoryapi-… [2] https://lore.kernel.org/all/20221014134802.1361436-1-mdanylo@google.com [3] https://github.com/google/sanitizers [4] https://github.com/google/sanitizers/wiki/AddressSanitizerAlgorithm#64-bit [5] https://lore.kernel.org/all/bfcae708-db21-04b4-0bbe-712badd03071@redhat.com [6] https://lore.kernel.org/all/20220725142048.30450-1-peterx@redhat.com/ [7] https://lore.kernel.org/all/20221122115007.2787017-1-usama.anjum@collabora.… [8] https://lore.kernel.org/all/20221220162606.1595355-1-usama.anjum@collabora.… [9] https://lore.kernel.org/all/20230306213925.617814-1-peterx@redhat.com [10] https://lore.kernel.org/all/20230125144529.1630917-1-mdanylo@google.com * Original Cover letter from v8* Hello, Note: Soft-dirty pages and pages which have been written-to are synonyms. As kernel already has soft-dirty feature inside which we have given up to use, we are using written-to terminology while using UFFD async WP under the hood. This IOCTL, PAGEMAP_SCAN on pagemap file can be used to get and/or clear the info about page table entries. The following operations are supported in this ioctl: - Get the information if the pages have been written-to (PAGE_IS_WRITTEN), file mapped (PAGE_IS_FILE), present (PAGE_IS_PRESENT) or swapped (PAGE_IS_SWAPPED). - Write-protect the pages (PAGEMAP_WP_ENGAGE) to start finding which pages have been written-to. - Find pages which have been written-to and write protect the pages (atomic PAGE_IS_WRITTEN + PAGEMAP_WP_ENGAGE) It is possible to find and clear soft-dirty pages entirely in userspace. But it isn't efficient: - The mprotect and SIGSEGV handler for bookkeeping - The userfaultfd wp (synchronous) with the handler for bookkeeping Some benchmarks can be seen here[1]. This series adds features that weren't present earlier: - There is no atomic get soft-dirty/Written-to status and clear present in the kernel. - The pages which have been written-to can not be found in accurate way. (Kernel's soft-dirty PTE bit + sof_dirty VMA bit shows more soft-dirty pages than there actually are.) Historically, soft-dirty PTE bit tracking has been used in the CRIU project. The procfs interface is enough for finding the soft-dirty bit status and clearing the soft-dirty bit of all the pages of a process. We have the use case where we need to track the soft-dirty PTE bit for only specific pages on-demand. We need this tracking and clear mechanism of a region of memory while the process is running to emulate the getWriteWatch() syscall of Windows. *(Moved to using UFFD instead of soft-dirtyi feature to find pages which have been written-to from v7 patch series)*: Stop using the soft-dirty flags for finding which pages have been written to. It is too delicate and wrong as it shows more soft-dirty pages than the actual soft-dirty pages. There is no interest in correcting it [2][3] as this is how the feature was written years ago. It shouldn't be updated to changed behaviour. Peter Xu has suggested using the async version of the UFFD WP [4] as it is based inherently on the PTEs. So in this patch series, I've added a new mode to the UFFD which is asynchronous version of the write protect. When this variant of the UFFD WP is used, the page faults are resolved automatically by the kernel. The pages which have been written-to can be found by reading pagemap file (!PM_UFFD_WP). This feature can be used successfully to find which pages have been written to from the time the pages were write protected. This works just like the soft-dirty flag without showing any extra pages which aren't soft-dirty in reality. The information related to pages if the page is file mapped, present and swapped is required for the CRIU project [5][6]. The addition of the required mask, any mask, excluded mask and return masks are also required for the CRIU project [5]. The IOCTL returns the addresses of the pages which match the specific masks. The page addresses are returned in struct page_region in a compact form. The max_pages is needed to support a use case where user only wants to get a specific number of pages. So there is no need to find all the pages of interest in the range when max_pages is specified. The IOCTL returns when the maximum number of the pages are found. The max_pages is optional. If max_pages is specified, it must be equal or greater than the vec_size. This restriction is needed to handle worse case when one page_region only contains info of one page and it cannot be compacted. This is needed to emulate the Windows getWriteWatch() syscall. The patch series include the detailed selftest which can be used as an example for the uffd async wp test and PAGEMAP_IOCTL. It shows the interface usages as well. [1] https://lore.kernel.org/lkml/54d4c322-cd6e-eefd-b161-2af2b56aae24@collabora… [2] https://lore.kernel.org/all/20221220162606.1595355-1-usama.anjum@collabora.… [3] https://lore.kernel.org/all/20221122115007.2787017-1-usama.anjum@collabora.… [4] https://lore.kernel.org/all/Y6Hc2d+7eTKs7AiH@x1n [5] https://lore.kernel.org/all/YyiDg79flhWoMDZB@gmail.com/ [6] https://lore.kernel.org/all/20221014134802.1361436-1-mdanylo@google.com/ Regards, Muhammad Usama Anjum Muhammad Usama Anjum (4): fs/proc/task_mmu: Implement IOCTL to get and optionally clear info about PTEs tools headers UAPI: Update linux/fs.h with the kernel sources mm/pagemap: add documentation of PAGEMAP_SCAN IOCTL selftests: mm: add pagemap ioctl tests Peter Xu (1): userfaultfd: UFFD_FEATURE_WP_ASYNC Documentation/admin-guide/mm/pagemap.rst | 58 + Documentation/admin-guide/mm/userfaultfd.rst | 35 + fs/proc/task_mmu.c | 503 ++++++ fs/userfaultfd.c | 26 +- include/linux/userfaultfd_k.h | 21 +- include/uapi/linux/fs.h | 53 + include/uapi/linux/userfaultfd.h | 9 +- mm/hugetlb.c | 32 +- mm/memory.c | 27 +- tools/include/uapi/linux/fs.h | 53 + tools/testing/selftests/mm/.gitignore | 1 + tools/testing/selftests/mm/Makefile | 3 +- tools/testing/selftests/mm/config | 1 + tools/testing/selftests/mm/pagemap_ioctl.c | 1459 ++++++++++++++++++ tools/testing/selftests/mm/run_vmtests.sh | 4 + 15 files changed, 2262 insertions(+), 23 deletions(-) create mode 100644 tools/testing/selftests/mm/pagemap_ioctl.c mode change 100644 => 100755 tools/testing/selftests/mm/run_vmtests.sh -- 2.39.2

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