Observed occassional failures in the futex_wait_timeout test:
ok 1 futex_wait relative succeeds
ok 2 futex_wait_bitset realtime succeeds
ok 3 futex_wait_bitset monotonic succeeds
ok 4 futex_wait_requeue_pi realtime succeeds
ok 5 futex_wait_requeue_pi monotonic succeeds
not ok 6 futex_lock_pi realtime returned 0
......
The test expects the child thread to complete some steps before
the parent thread gets to run. There is an implicit expectation
of the order of invocation of futex_lock_pi between the child thread
and the parent thread. Make this order explicit. If the order is
not met, the futex_lock_pi call in the parent thread succeeds and
will not timeout.
Fixes: f4addd54b161 ("selftests: futex: Expand timeout test")
Signed-off-by: Nysal Jan K.A <nysal(a)linux.ibm.com>
---
.../selftests/futex/functional/futex_wait_timeout.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/tools/testing/selftests/futex/functional/futex_wait_timeout.c b/tools/testing/selftests/futex/functional/futex_wait_timeout.c
index 3651ce17beeb..d183f878360b 100644
--- a/tools/testing/selftests/futex/functional/futex_wait_timeout.c
+++ b/tools/testing/selftests/futex/functional/futex_wait_timeout.c
@@ -24,6 +24,7 @@
static long timeout_ns = 100000; /* 100us default timeout */
static futex_t futex_pi;
+static pthread_barrier_t barrier;
void usage(char *prog)
{
@@ -48,6 +49,8 @@ void *get_pi_lock(void *arg)
if (ret != 0)
error("futex_lock_pi failed\n", ret);
+ pthread_barrier_wait(&barrier);
+
/* Blocks forever */
ret = futex_wait(&lock, 0, NULL, 0);
error("futex_wait failed\n", ret);
@@ -130,6 +133,7 @@ int main(int argc, char *argv[])
basename(argv[0]));
ksft_print_msg("\tArguments: timeout=%ldns\n", timeout_ns);
+ pthread_barrier_init(&barrier, NULL, 2);
pthread_create(&thread, NULL, get_pi_lock, NULL);
/* initialize relative timeout */
@@ -163,6 +167,9 @@ int main(int argc, char *argv[])
res = futex_wait_requeue_pi(&f1, f1, &futex_pi, &to, 0);
test_timeout(res, &ret, "futex_wait_requeue_pi monotonic", ETIMEDOUT);
+ /* Wait until the other thread calls futex_lock_pi() */
+ pthread_barrier_wait(&barrier);
+ pthread_barrier_destroy(&barrier);
/*
* FUTEX_LOCK_PI with CLOCK_REALTIME
* Due to historical reasons, FUTEX_LOCK_PI supports only realtime
--
2.41.0
The user_events selftests were removed from the standard set of
selftests due to the uapi header it relies on having been temporarily
removed. That header is now reinstated so we can reenable the tests.
Signed-off-by: Mark Brown <broonie(a)kernel.org>
---
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/user_events/Makefile | 8 --------
2 files changed, 1 insertion(+), 8 deletions(-)
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 666b56f22a41..4e221bb620b4 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -89,6 +89,7 @@ TARGETS += tmpfs
TARGETS += tpm2
TARGETS += tty
TARGETS += user
+TARGETS += user_events
TARGETS += vDSO
TARGETS += mm
TARGETS += x86
diff --git a/tools/testing/selftests/user_events/Makefile b/tools/testing/selftests/user_events/Makefile
index 9e95bd41b0b4..10fcd0066203 100644
--- a/tools/testing/selftests/user_events/Makefile
+++ b/tools/testing/selftests/user_events/Makefile
@@ -2,14 +2,6 @@
CFLAGS += -Wl,-no-as-needed -Wall $(KHDR_INCLUDES)
LDLIBS += -lrt -lpthread -lm
-# Note:
-# This test depends on <linux/user_events.h> exported in uapi
-# The following commit removed user_events.h out of uapi:
-# commit 5cfff569cab8bf544bab62c911c5d6efd5af5e05
-# tracing: Move user_events.h temporarily out of include/uapi
-# This test will not compile until user_events.h is added
-# back to uapi.
-
TEST_GEN_PROGS = ftrace_test dyn_test perf_test abi_test
TEST_FILES := settings
---
base-commit: 5d0c230f1de8c7515b6567d9afba1f196fb4e2f4
change-id: 20230805-kselftest-user-events-e4beff821b0f
Best regards,
--
Mark Brown <broonie(a)kernel.org>
We have some dmabuf-heaps and perf_events tests but they are not hooked
up to the kselftest build infrastructure which is a bit of an obstacle
to running them in systems with generic infrastructure for selftests.
Add them to the top level kselftest Makefile so they get built as
standard.
Signed-off-by: Mark Brown <broonie(a)kernel.org>
---
tools/testing/selftests/Makefile | 3 +++
1 file changed, 3 insertions(+)
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 666b56f22a41..bdee501596ef 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -12,6 +12,7 @@ TARGETS += core
TARGETS += cpufreq
TARGETS += cpu-hotplug
TARGETS += damon
+TARGETS += dmabuf-heaps
TARGETS += drivers/dma-buf
TARGETS += drivers/s390x/uvdevice
TARGETS += drivers/net/bonding
@@ -56,6 +57,7 @@ TARGETS += net/mptcp
TARGETS += net/openvswitch
TARGETS += netfilter
TARGETS += nsfs
+TARGETS += perf_events
TARGETS += pidfd
TARGETS += pid_namespace
TARGETS += powerpc
@@ -88,6 +90,7 @@ endif
TARGETS += tmpfs
TARGETS += tpm2
TARGETS += tty
+TARGETS += uevents
TARGETS += user
TARGETS += vDSO
TARGETS += mm
---
base-commit: 5d0c230f1de8c7515b6567d9afba1f196fb4e2f4
change-id: 20230805-kselftest-perf-events-build-c0e0f1182bae
Best regards,
--
Mark Brown <broonie(a)kernel.org>
In busybox, the mktemp requires that the generated filename be
suffixed with at least six consecutive 'X' characters. Otherwise,
it will return an "Invalid argument" error.
Signed-off-by: Hui Min Mina Chou <minachou(a)andestech.com>
---
tools/testing/selftests/filesystems/fat/run_fat_tests.sh | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/testing/selftests/filesystems/fat/run_fat_tests.sh b/tools/testing/selftests/filesystems/fat/run_fat_tests.sh
index 7f35dc3d15df..d61264d4795d 100755
--- a/tools/testing/selftests/filesystems/fat/run_fat_tests.sh
+++ b/tools/testing/selftests/filesystems/fat/run_fat_tests.sh
@@ -12,7 +12,7 @@ set -u
set -o pipefail
BASE_DIR="$(dirname $0)"
-TMP_DIR="$(mktemp -d /tmp/fat_tests_tmp.XXXX)"
+TMP_DIR="$(mktemp -d /tmp/fat_tests_tmp.XXXXXX)"
IMG_PATH="${TMP_DIR}/fat.img"
MNT_PATH="${TMP_DIR}/mnt"
--
2.34.1
lwt xmit hook does not expect positive return values in function
ip_finish_output2 and ip6_finish_output. However, BPF programs can
directly return positive statuses such like NET_XMIT_DROP, NET_RX_DROP,
and etc to the caller. Such return values would make the kernel continue
processing already freed skbs and eventually panic.
This set fixes the return values from BPF ops to unexpected continue
processing, and checks strictly on the correct continue condition for
future proof. In addition, add missing selftests for BPF_REDIRECT
and BPF_REROUTE cases for BPF-CI.
v4: https://lore.kernel.org/bpf/ZMD1sFTW8SFiex+x@debian.debian/T/
v3: https://lore.kernel.org/bpf/cover.1690255889.git.yan@cloudflare.com/
v2: https://lore.kernel.org/netdev/ZLdY6JkWRccunvu0@debian.debian/
v1: https://lore.kernel.org/bpf/ZLbYdpWC8zt9EJtq@debian.debian/
changes since v4:
* fixed same error on BPF_REROUTE path
* re-implemented selftests under BPF-CI requirement
changes since v3:
* minor change in commit message and changelogs
* tested by Jakub Sitnicki
changes since v2:
* subject name changed
* also covered redirect to ingress case
* added selftests
changes since v1:
* minor code style changes
Yan Zhai (4):
lwt: fix return values of BPF ops
lwt: check LWTUNNEL_XMIT_CONTINUE strictly
selftests/bpf: add lwt_xmit tests for BPF_REDIRECT
selftests/bpf: add lwt_xmit tests for BPF_REROUTE
include/net/lwtunnel.h | 5 +-
net/core/lwt_bpf.c | 7 +-
net/ipv4/ip_output.c | 2 +-
net/ipv6/ip6_output.c | 2 +-
.../selftests/bpf/prog_tests/lwt_helpers.h | 139 ++++++++
.../selftests/bpf/prog_tests/lwt_redirect.c | 319 ++++++++++++++++++
.../selftests/bpf/prog_tests/lwt_reroute.c | 256 ++++++++++++++
.../selftests/bpf/progs/test_lwt_redirect.c | 58 ++++
.../selftests/bpf/progs/test_lwt_reroute.c | 36 ++
9 files changed, 817 insertions(+), 7 deletions(-)
create mode 100644 tools/testing/selftests/bpf/prog_tests/lwt_helpers.h
create mode 100644 tools/testing/selftests/bpf/prog_tests/lwt_redirect.c
create mode 100644 tools/testing/selftests/bpf/prog_tests/lwt_reroute.c
create mode 100644 tools/testing/selftests/bpf/progs/test_lwt_redirect.c
create mode 100644 tools/testing/selftests/bpf/progs/test_lwt_reroute.c
--
2.30.2
Hi Shuah, hi Paul,
I'm sending you the list of planned nolibc changes for 6.6. A doc update
may possibly follow a bit later to try to document the contribution
process. We also noticed a slight increase in binary sizes that might
be fixed soon but I wouldn't bet on this since it will require lot of
testing again and I'd rather postpone this by default. In any case I
have no intent to push any significant updates/fixes for 6.6 at this
point.
I'm also pasting a summary of the changes in this pull request, feel
free to use it for the merge commit message if you need.
For any question or if anything is not clear, do not hesitate to ask!
Thanks,
Willy
----- changes ------
Nolibc:
- improved portability by removing build errors with -ENOSYS
- added syscall6() on MIPS to support pselect6() and mmap()
- added setvbuf(), rmdir(), pipe(), pipe2()
- add support for ppc/ppc64
- environ is no longer optional
- fixed frame pointer issues at -O0
- dropped sys_stat() in favor of sys_statx()
- centralized _start_c() to remove lots of asm code
- switched size_t to __SIZE_TYPE__
Selftests:
- improved status reporting (success/warning/failure counts, path to log file)
- various code cleanups (indent, unused variables, ...)
- more consistent test numbering
- enabled compiler warnings
- dropped unreliable chmod_net test
- improved reliability (create /dev/zero & /tmp, rely less on /proc)
- new tests (brk/sbrk/mmap/munmap)
- improved compatibility with musl
- new run-nolibc-test target to build and run natively
- new run-libc-test target to build and run against native libc
- made the cmdline parser more reliable against boolean arguments
- dropped dependency on memfd for vfprintf() test
- nolibc-test is no longer stripped
- added support for extending ARCH via XARCH
Other:
- add Thomas as co-maintainer
-----------
The following changes since commit 06c2afb862f9da8dc5efa4b6076a0e48c3fbaaa5:
Linux 6.5-rc1 (2023-07-09 13:53:13 -0700)
are available in the Git repository at:
https://git.kernel.org/pub/scm/linux/kernel/git/wtarreau/nolibc.git/ 20230806-for-6.6-1
for you to fetch changes up to d98c1e27e46e47a3ae67e1d048f153598ba82611:
tools/nolibc: stackprotector.h: make __stack_chk_init static (2023-08-06 18:44:47 +0200)
----------------------------------------------------------------
Ryan Roberts (1):
tools/nolibc/stdio: add setvbuf() to set buffering mode
Thomas Weißschuh (22):
selftests/nolibc: drop test chmod_net
selftests/nolibc: simplify call to ioperm
tools/nolibc: completely remove optional environ support
selftests/nolibc: make evaluation of test conditions
selftests/nolibc: simplify status printing
selftests/nolibc: avoid gaps in test numbers
selftests/nolibc: avoid buffer underrun in space printing
tools/nolibc: drop unused variables
tools/nolibc: fix return type of getpagesize()
tools/nolibc: setvbuf: avoid unused parameter warnings
tools/nolibc: sys: avoid implicit sign cast
tools/nolibc: stdint: use __SIZE_TYPE__ for size_t
selftests/nolibc: drop unused variables
selftests/nolibc: mark test helpers as potentially unused
selftests/nolibc: make functions static if possible
selftests/nolibc: avoid unused parameter warnings
selftests/nolibc: avoid sign-compare warnings
selftests/nolibc: use correct return type for read() and write()
selftests/nolibc: prevent out of bounds access in expect_vfprintf
selftests/nolibc: don't strip nolibc-test
selftests/nolibc: enable compiler warnings
MAINTAINERS: nolibc: add myself as co-maintainer
Willy Tarreau (1):
selftests/nolibc: avoid warnings during intptr tests
Yuan Tan (2):
tools/nolibc: add pipe() and pipe2() support
selftests/nolibc: add testcase for pipe
Zhangjin Wu (74):
selftests/nolibc: add a standalone test report macro
selftests/nolibc: always print the path to test log file
selftests/nolibc: restore the failed tests print
tools/nolibc: fix up #error compile failures with -ENOSYS
tools/nolibc: fix up undeclared syscall macros with #ifdef and -ENOSYS
tools/nolibc: sys.h: add a syscall return helper
tools/nolibc: unistd.h: apply __sysret() helper
tools/nolibc: sys.h: apply __sysret() helper
tools/nolibc: unistd.h: reorder the syscall macros
tools/nolibc: arch-*.h: fix up code indent errors
toolc/nolibc: arch-*.h: clean up whitespaces after __asm__
tools/nolibc: arch-loongarch.h: shrink with _NOLIBC_SYSCALL_CLOBBERLIST
tools/nolibc: arch-mips.h: shrink with _NOLIBC_SYSCALL_CLOBBERLIST
tools/nolibc: add missing my_syscall6() for mips
tools/nolibc: __sysret: support syscalls who return a pointer
tools/nolibc: clean up mmap() routine
tools/nolibc: clean up sbrk() routine
selftests/nolibc: export argv0 for some tests
selftests/nolibc: prepare: create /dev/zero
selftests/nolibc: add EXPECT_PTREQ, EXPECT_PTRNE and EXPECT_PTRER
selftests/nolibc: add sbrk_0 to test current brk getting
selftests/nolibc: add mmap_bad test case
selftests/nolibc: add munmap_bad test case
selftests/nolibc: add mmap_munmap_good test case
selftests/nolibc: add run-libc-test target
selftests/nolibc: stat_fault: silence NULL argument warning with glibc
selftests/nolibc: gettid: restore for glibc and musl
selftests/nolibc: add _LARGEFILE64_SOURCE for musl
selftests/nolibc: fix up int_fast16/32_t test cases for musl
tools/nolibc: types.h: add RB_ flags for reboot()
selftests/nolibc: prefer <sys/reboot.h> to <linux/reboot.h>
selftests/nolibc: fix up kernel parameters support
selftests/nolibc: link_cross: use /proc/self/cmdline
tools/nolibc: add rmdir() support
selftests/nolibc: add a new rmdir() test case
selftests/nolibc: fix up failures when CONFIG_PROC_FS=n
selftests/nolibc: prepare /tmp for tests that need to write
selftests/nolibc: vfprintf: remove MEMFD_CREATE dependency
selftests/nolibc: chdir_root: restore current path after test
selftests/nolibc: stat_timestamps: remove procfs dependency
selftests/nolibc: chroot_exe: remove procfs dependency
selftests/nolibc: add chmod_argv0 test
selftests/nolibc: report: print a summarized test status
selftests/nolibc: report: print total tests
selftests/nolibc: report: align passed, skipped and failed
selftests/nolibc: report: extrude the test status line
selftests/nolibc: report: add newline before test failures
tools/nolibc: arch-*.h: add missing space after ','
tools/nolibc: fix up startup failures for -O0 under gcc < 11.1.0
tools/nolibc: remove the old sys_stat support
tools/nolibc: add new crt.h with _start_c
tools/nolibc: stackprotector.h: add empty __stack_chk_init for !_NOLIBC_STACKPROTECTOR
tools/nolibc: crt.h: initialize stack protector
tools/nolibc: arm: shrink _start with _start_c
tools/nolibc: aarch64: shrink _start with _start_c
tools/nolibc: i386: shrink _start with _start_c
tools/nolibc: x86_64: shrink _start with _start_c
tools/nolibc: mips: shrink _start with _start_c
tools/nolibc: loongarch: shrink _start with _start_c
tools/nolibc: riscv: shrink _start with _start_c
tools/nolibc: s390: shrink _start with _start_c
selftests/nolibc: add EXPECT_PTRGE, EXPECT_PTRGT, EXPECT_PTRLE, EXPECT_PTRLT
selftests/nolibc: add testcases for startup code
selftests/nolibc: allow run nolibc-test locally
selftests/nolibc: allow test -include /path/to/nolibc.h
selftests/nolibc: mmap_munmap_good: fix up return value
tools/nolibc: add support for powerpc
tools/nolibc: add support for powerpc64
selftests/nolibc: add XARCH and ARCH mapping support
selftests/nolibc: add test support for ppc
selftests/nolibc: add test support for ppc64le
selftests/nolibc: add test support for ppc64
selftests/nolibc: allow report with existing test log
tools/nolibc: stackprotector.h: make __stack_chk_init static
MAINTAINERS | 1 +
tools/include/nolibc/Makefile | 1 +
tools/include/nolibc/arch-aarch64.h | 85 +---
tools/include/nolibc/arch-arm.h | 111 +----
tools/include/nolibc/arch-i386.h | 86 +---
tools/include/nolibc/arch-loongarch.h | 83 +---
tools/include/nolibc/arch-mips.h | 147 +++----
tools/include/nolibc/arch-powerpc.h | 213 ++++++++++
tools/include/nolibc/arch-riscv.h | 83 +---
tools/include/nolibc/arch-s390.h | 77 +---
tools/include/nolibc/arch-x86_64.h | 86 +---
tools/include/nolibc/arch.h | 2 +
tools/include/nolibc/crt.h | 61 +++
tools/include/nolibc/nolibc.h | 9 +-
tools/include/nolibc/stackprotector.h | 5 +-
tools/include/nolibc/stdint.h | 2 +-
tools/include/nolibc/stdio.h | 27 ++
tools/include/nolibc/stdlib.h | 12 +-
tools/include/nolibc/sys.h | 554 +++++++-----------------
tools/include/nolibc/types.h | 22 +-
tools/include/nolibc/unistd.h | 13 +-
tools/testing/selftests/nolibc/Makefile | 109 +++--
tools/testing/selftests/nolibc/nolibc-test.c | 609 ++++++++++++++++++++-------
23 files changed, 1216 insertions(+), 1182 deletions(-)
create mode 100644 tools/include/nolibc/arch-powerpc.h
create mode 100644 tools/include/nolibc/crt.h
When run command "ip netns delete client", device link1_1 has been
deleted. So, it is no need to delete link1_1 again. Remove it.
Signed-off-by: Zhengchao Shao <shaozhengchao(a)huawei.com>
---
.../drivers/net/bonding/bond-arp-interval-causes-panic.sh | 1 -
1 file changed, 1 deletion(-)
diff --git a/tools/testing/selftests/drivers/net/bonding/bond-arp-interval-causes-panic.sh b/tools/testing/selftests/drivers/net/bonding/bond-arp-interval-causes-panic.sh
index 71c00bfafbc9..7b2d421f09cf 100755
--- a/tools/testing/selftests/drivers/net/bonding/bond-arp-interval-causes-panic.sh
+++ b/tools/testing/selftests/drivers/net/bonding/bond-arp-interval-causes-panic.sh
@@ -11,7 +11,6 @@ finish()
{
ip netns delete server || true
ip netns delete client || true
- ip link del link1_1 || true
}
trap finish EXIT
--
2.34.1
*Changes in v30*:
- Rebase on top of next-20230815
- Minor nitpicks
*Changes in v29:*
- Polish IOCTL and improve documentation
*Changes in v28:*
- Fix walk_end and add 17 test cases in selftests patch
*Changes in v27:*
- Handle review comments and minor improvements
- Add performance improvement patch on top with test for easy review
*Changes in v26:*
- Code re-structurring and API changes in PAGEMAP_IOCTL
*Changes in v25*:
- Do proper filtering on hole as well (hole got missed earlier)
*Changes in v24*:
- Rebase on top of next-20230710
- Place WP markers in case of hole as well
*Changes in v23*:
- Set vec_buf_index in loop only when vec_buf_index is set
- Return -EFAULT instead of -EINVAL if vec is NULL
- Correctly return the walk ending address to the page granularity
*Changes in v22*:
- Interface change:
- Replace [start start + len) with [start, end)
- Return the ending address of the address walk in start
*Changes in v21*:
- Abort walk instead of returning error if WP is to be performed on
partial hugetlb
*Changes in v20*
- Correct PAGE_IS_FILE and add PAGE_IS_PFNZERO
*Changes in v19*
- Minor changes and interface updates
*Changes in v18*
- Rebase on top of next-20230613
- Minor updates
*Changes in v17*
- Rebase on top of next-20230606
- Minor improvements in PAGEMAP_SCAN IOCTL patch
*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() and ResetWriteWatch() syscalls [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.
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-dirty 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 (5):
fs/proc/task_mmu: Implement IOCTL to get and optionally clear info
about PTEs
fs/proc/task_mmu: Add fast paths to get/clear PAGE_IS_WRITTEN flag
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 | 89 +
Documentation/admin-guide/mm/userfaultfd.rst | 35 +
fs/proc/task_mmu.c | 708 ++++++++
fs/userfaultfd.c | 26 +-
include/linux/hugetlb.h | 1 +
include/linux/userfaultfd_k.h | 28 +-
include/uapi/linux/fs.h | 59 +
include/uapi/linux/userfaultfd.h | 9 +-
mm/hugetlb.c | 34 +-
mm/memory.c | 28 +-
tools/include/uapi/linux/fs.h | 59 +
tools/testing/selftests/mm/.gitignore | 2 +
tools/testing/selftests/mm/Makefile | 3 +-
tools/testing/selftests/mm/config | 1 +
tools/testing/selftests/mm/pagemap_ioctl.c | 1660 ++++++++++++++++++
tools/testing/selftests/mm/run_vmtests.sh | 4 +
16 files changed, 2722 insertions(+), 24 deletions(-)
create mode 100644 tools/testing/selftests/mm/pagemap_ioctl.c
--
2.40.1
*Changes in v30*:
- Rebase on top of next-20230815
- Minor nitpicks
*Changes in v29:*
- Polish IOCTL and improve documentation
*Changes in v28:*
- Fix walk_end and add 17 test cases in selftests patch
*Changes in v27:*
- Handle review comments and minor improvements
- Add performance improvement patch on top with test for easy review
*Changes in v26:*
- Code re-structurring and API changes in PAGEMAP_IOCTL
*Changes in v25*:
- Do proper filtering on hole as well (hole got missed earlier)
*Changes in v24*:
- Rebase on top of next-20230710
- Place WP markers in case of hole as well
*Changes in v23*:
- Set vec_buf_index in loop only when vec_buf_index is set
- Return -EFAULT instead of -EINVAL if vec is NULL
- Correctly return the walk ending address to the page granularity
*Changes in v22*:
- Interface change:
- Replace [start start + len) with [start, end)
- Return the ending address of the address walk in start
*Changes in v21*:
- Abort walk instead of returning error if WP is to be performed on
partial hugetlb
*Changes in v20*
- Correct PAGE_IS_FILE and add PAGE_IS_PFNZERO
*Changes in v19*
- Minor changes and interface updates
*Changes in v18*
- Rebase on top of next-20230613
- Minor updates
*Changes in v17*
- Rebase on top of next-20230606
- Minor improvements in PAGEMAP_SCAN IOCTL patch
*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() and ResetWriteWatch() syscalls [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.
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-dirty 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 (5):
fs/proc/task_mmu: Implement IOCTL to get and optionally clear info
about PTEs
fs/proc/task_mmu: Add fast paths to get/clear PAGE_IS_WRITTEN flag
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 | 89 +
Documentation/admin-guide/mm/userfaultfd.rst | 35 +
fs/proc/task_mmu.c | 705 ++++++++
fs/userfaultfd.c | 26 +-
include/linux/hugetlb.h | 1 +
include/linux/userfaultfd_k.h | 28 +-
include/uapi/linux/fs.h | 59 +
include/uapi/linux/userfaultfd.h | 9 +-
mm/hugetlb.c | 34 +-
mm/memory.c | 28 +-
tools/include/uapi/linux/fs.h | 59 +
tools/testing/selftests/mm/.gitignore | 2 +
tools/testing/selftests/mm/Makefile | 3 +-
tools/testing/selftests/mm/config | 1 +
tools/testing/selftests/mm/pagemap_ioctl.c | 1660 ++++++++++++++++++
tools/testing/selftests/mm/run_vmtests.sh | 4 +
16 files changed, 2719 insertions(+), 24 deletions(-)
create mode 100644 tools/testing/selftests/mm/pagemap_ioctl.c
--
2.40.1