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

[PATCH v2 1/2] Add polling support to pidfd

by Joel Fernandes (Google)

Android low memory killer (LMK) needs to know when a process dies once it is sent the kill signal. It does so by checking for the existence of /proc/pid which is both racy and slow. For example, if a PID is reused between when LMK sends a kill signal and checks for existence of the PID, since the wrong PID is now possibly checked for existence. This patch adds polling support to pidfd. Using the polling support, LMK will be able to get notified when a process exists in race-free and fast way, and allows the LMK to do other things (such as by polling on other fds) while awaiting the process being killed to die. For notification to polling processes, we follow the same existing mechanism in the kernel used when the parent of the task group is to be notified of a child's death (do_notify_parent). This is precisely when the tasks waiting on a poll of pidfd are also awakened in this patch. We have decided to include the waitqueue in struct pid for the following reasons: 1. The wait queue has to survive for the lifetime of the poll. Including it in task_struct would not be option in this case because the task can be reaped and destroyed before the poll returns. 2. By including the struct pid for the waitqueue means that during de_thread(), the new thread group leader automatically gets the new waitqueue/pid even though its task_struct is different. Appropriate test cases are added in the second patch to provide coverage of all the cases the patch is handling. Andy had a similar patch [1] in the past which was a good reference however this patch tries to handle different situations properly related to thread group existence, and how/where it notifies. And also solves other bugs (waitqueue lifetime). Daniel had a similar patch [2] recently which this patch supercedes. [1] https://lore.kernel.org/patchwork/patch/345098/ [2] https://lore.kernel.org/lkml/20181029175322.189042-1-dancol@google.com/ Cc: Andy Lutomirski <luto(a)amacapital.net> Cc: Steven Rostedt <rostedt(a)goodmis.org> Cc: Daniel Colascione <dancol(a)google.com> Cc: Christian Brauner <christian(a)brauner.io> Cc: Jann Horn <jannh(a)google.com> Cc: Tim Murray <timmurray(a)google.com> Cc: Jonathan Kowalski <bl0pbl33p(a)gmail.com> Cc: Linus Torvalds <torvalds(a)linux-foundation.org> Cc: Al Viro <viro(a)zeniv.linux.org.uk> Cc: Kees Cook <keescook(a)chromium.org> Cc: David Howells <dhowells(a)redhat.com> Cc: Oleg Nesterov <oleg(a)redhat.com> Cc: kernel-team(a)android.com (Oleg improved the code by showing how to avoid tasklist_lock) Suggested-by: Oleg Nesterov <oleg(a)redhat.com> Co-developed-by: Daniel Colascione <dancol(a)google.com> Signed-off-by: Daniel Colascione <dancol(a)google.com> Signed-off-by: Joel Fernandes (Google) <joel(a)joelfernandes.org> --- v1 -> v2: * Restructure poll code to avoid tasklist_lock (Oleg) * use task_pid instead of get_pid_task in notify_pidfd (Oleg) * Added comments to code, commit message nits (Christian) * Test case nits/improvements (Christian) RFC -> v1: * Based on CLONE_PIDFD patches: https://lwn.net/Articles/786244/ * Updated selftests. * Renamed poll wake function to do_notify_pidfd. * Removed depending on EXIT flags * Removed POLLERR flag since semantics are controversial and we don't have usecases for it right now (later we can add if there's a need for it). include/linux/pid.h | 3 +++ kernel/fork.c | 29 +++++++++++++++++++++++++++++ kernel/pid.c | 2 ++ kernel/signal.c | 11 +++++++++++ 4 files changed, 45 insertions(+) diff --git a/include/linux/pid.h b/include/linux/pid.h index 3c8ef5a199ca..1484db6ca8d1 100644 --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -3,6 +3,7 @@ #define _LINUX_PID_H #include <linux/rculist.h> +#include <linux/wait.h> enum pid_type { @@ -60,6 +61,8 @@ struct pid unsigned int level; /* lists of tasks that use this pid */ struct hlist_head tasks[PIDTYPE_MAX]; + /* wait queue for pidfd notifications */ + wait_queue_head_t wait_pidfd; struct rcu_head rcu; struct upid numbers[1]; }; diff --git a/kernel/fork.c b/kernel/fork.c index 5525837ed80e..721f8c9d2921 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1685,8 +1685,37 @@ static void pidfd_show_fdinfo(struct seq_file *m, struct file *f) } #endif +/* + * Poll support for process exit notification. + */ +static unsigned int pidfd_poll(struct file *file, struct poll_table_struct *pts) +{ + struct task_struct *task; + struct pid *pid = file->private_data; + int poll_flags = 0; + + poll_wait(file, &pid->wait_pidfd, pts); + + rcu_read_lock(); + task = pid_task(pid, PIDTYPE_PID); + WARN_ON_ONCE(task && !thread_group_leader(task)); + + /* + * Inform pollers only when the whole thread group exits, if thread + * group leader exits before all other threads in the group, then + * poll(2) should block, similar to the wait(2) family. + */ + if (!task || (task->exit_state && thread_group_empty(task))) + poll_flags = POLLIN | POLLRDNORM; + rcu_read_unlock(); + + return poll_flags; +} + + const struct file_operations pidfd_fops = { .release = pidfd_release, + .poll = pidfd_poll, #ifdef CONFIG_PROC_FS .show_fdinfo = pidfd_show_fdinfo, #endif diff --git a/kernel/pid.c b/kernel/pid.c index 20881598bdfa..5c90c239242f 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -214,6 +214,8 @@ struct pid *alloc_pid(struct pid_namespace *ns) for (type = 0; type < PIDTYPE_MAX; ++type) INIT_HLIST_HEAD(&pid->tasks[type]); + init_waitqueue_head(&pid->wait_pidfd); + upid = pid->numbers + ns->level; spin_lock_irq(&pidmap_lock); if (!(ns->pid_allocated & PIDNS_ADDING)) diff --git a/kernel/signal.c b/kernel/signal.c index 1581140f2d99..a17fff073c3d 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1800,6 +1800,14 @@ int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type) return ret; } +static void do_notify_pidfd(struct task_struct *task) +{ + struct pid *pid; + + pid = task_pid(task); + wake_up_all(&pid->wait_pidfd); +} + /* * Let a parent know about the death of a child. * For a stopped/continued status change, use do_notify_parent_cldstop instead. @@ -1823,6 +1831,9 @@ bool do_notify_parent(struct task_struct *tsk, int sig) BUG_ON(!tsk->ptrace && (tsk->group_leader != tsk || !thread_group_empty(tsk))); + /* Wake up all pidfd waiters */ + do_notify_pidfd(tsk); + if (sig != SIGCHLD) { /* * This is only possible if parent == real_parent. -- 2.21.0.593.g511ec345e18-goog

6 years, 4 months

4
10
0 0

[PATCH v2] selftests: kvm: Add files generated when compiled to .gitignore

by Kelsey Skunberg

The following files are generated in /selftests/kvm/ after compiling and should be added to /selftests/kvm/.gitignore: - /x86_64/hyperv_cpuid - /x86_64/smm_test - /clear_dirty_log_test Signed-off-by: Kelsey Skunberg <skunberg.kelsey(a)gmail.com> --- Changes since v1: - Included /clear_dirty_log_test to .gitignore - Updated commit log to reflect file added tools/testing/selftests/kvm/.gitignore | 3 +++ 1 file changed, 3 insertions(+) diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore index 2689d1ea6d7a..391a19231618 100644 --- a/tools/testing/selftests/kvm/.gitignore +++ b/tools/testing/selftests/kvm/.gitignore @@ -6,4 +6,7 @@ /x86_64/vmx_close_while_nested_test /x86_64/vmx_tsc_adjust_test /x86_64/state_test +/x86_64/hyperv_cpuid +/x86_64/smm_test +/clear_dirty_log_test /dirty_log_test -- 2.20.1

6 years, 4 months

2
1
0 0

selftests: bpf: test_sock: WARNING: workqueue.c:3030 __flush_work+0x3fc/0x470

by Naresh Kamboju

Do you see kernel WARNING while running bpf: test_sock test case ? This kernel warning is popping up continuously for ~725 times on all devices ( arm64, arm, x86_64 and i386). selftests: bpf: test_sock Test case: bind4 load with invalid access: src_ip6 .. [PASS] Test case: bind4 load with invalid access: mark .. [PASS] Test case: bind6 load with invalid access: src_ip4 .. [PASS] Test case: sock_create load with invalid access: src_port .. [PASS] Test case: sock_create load w/o expected_attach_type (compat mode) .. [PASS] Test case: sock_create load w/ expected_attach_type .. [PASS] Test case: attach type mismatch bind4 vs bind6 .. [PASS] Test case: attach type mismatch bind6 vs bind4 .. [PASS] Test case: attach type mismatch default vs bind4 .. [PASS] Test case: attach type mismatch bind6 vs sock_create .. [PASS] Test case: bind4 reject all .. [PASS] Test case: bind6 reject all .. [PASS] Test case: bind6 deny specific IP & port .. [PASS] Test case: bind4 allow specific IP & port .. [PASS] Test case: bind4 allow all .. [PASS] Test case: bind6 allow all .. [PASS] Summ[ 200.359313] WARNING: CPU: 1 PID: 3400 at /usr/src/kernel/kernel/workqueue.c:3030 __flush_work+0x3fc/0x470 [ 200.369390] Modules linked in: tun algif_hash af_alg x86_pkg_temp_thermal fuse [ 200.376621] CPU: 1 PID: 3400 Comm: kworker/1:156 Not tainted 5.1.0 #1 [ 200.383061] Hardware name: Supermicro SYS-5019S-ML/X11SSH-F, BIOS 2.2 05/23/2018 [ 200.390455] Workqueue: events sk_psock_destroy_deferred [ 200.395679] RIP: 0010:__flush_work+0x3fc/0x470 [ 200.400123] Code: 03 00 31 c0 e9 a4 fe ff ff 41 8b 0c 24 49 8b 54 24 08 83 e1 08 49 0f ba 2c 24 03 80 c9 f0 e9 d0 fd ff ff 0f 0b e9 83 fe ff ff <0f> 0b 31 c0 e9 7a fe ff ff e8 e6 1f 06 00 84 c0 0f 85 fd fe ff ff [ 200.418859] RSP: 0018:ffffa5d68487bca0 EFLAGS: 00010246 [ 200.424079] RAX: 0000000000000000 RBX: ffff9abc19269468 RCX: 0000000000000006 [ 200.431200] RDX: 0000000000001b35 RSI: 0000000000000001 RDI: ffff9abc19269468 [ 200.438324] RBP: ffffa5d68487bd68 R08: 0000000000000000 R09: 0000000000000000 [ 200.445449] R10: 0000000000000000 R11: 0000000000000000 R12: ffff9abc19269468 [ 200.452572] R13: 0000000000000001 R14: ffffa5d68487bd98 R15: ffffffffabe91000 [ 200.459696] FS: 0000000000000000(0000) GS:ffff9abc6f880000(0000) knlGS:0000000000000000 [ 200.467776] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 200.473521] CR2: 00007f6c3ebf3cb0 CR3: 00000001d920a006 CR4: 00000000003606e0 [ 200.480644] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 200.487768] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 200.494891] Call Trace: [ 200.497338] ? get_work_pool+0x90/0x90 [ 200.501090] ? mark_held_locks+0x4d/0x80 [ 200.505015] ? __cancel_work_timer+0x11a/0x1d0 [ 200.509452] ? cancel_delayed_work_sync+0x13/0x20 [ 200.514151] ? lockdep_hardirqs_on+0xf6/0x190 [ 200.518509] ? __cancel_work_timer+0x11a/0x1d0 [ 200.522946] ? get_work_pool+0x90/0x90 [ 200.526691] __cancel_work_timer+0x134/0x1d0 [ 200.530965] cancel_delayed_work_sync+0x13/0x20 [ 200.535497] strp_done+0x1c/0x50 [ 200.538729] sk_psock_destroy_deferred+0x34/0x1c0 [ 200.543434] process_one_work+0x281/0x610 [ 200.547439] worker_thread+0x3c/0x3f0 [ 200.551105] kthread+0x12c/0x150 [ 200.554337] ? process_one_work+0x610/0x610 [ 200.558515] ? kthread_park+0x90/0x90 [ 200.562180] ret_from_fork+0x3a/0x50 [ 200.565762] irq event stamp: 2382 [ 200.569079] hardirqs last enabled at (2381): [<ffffffffabe9569a>] __cancel_work_timer+0x11a/0x1d0 [ 200.578030] hardirqs last disabled at (2382): [<ffffffffabe01b7b>] trace_hardirqs_off_thunk+0x1a/0x1c [ 200.587234] softirqs last enabled at (1806): [<fffffffface00334>] __do_softirq+0x334/0x445 [ 200.595573] softirqs last disabled at (1761): [<ffffffffabe76e70>] irq_exit+0xc0/0xd0 [ 200.603398] ---[ end trace 447ba7732b3f8640 ]--- Test full log link, https://qa-reports.linaro.org/lkft/linux-mainline-oe/build/v5.1-9822-g47782… Best regards Naresh Kamboju

6 years, 4 months

1
0
0 0

next-20190513 kselftest results

by ci_notify＠linaro.org

Summary ------------------------------------------------------------------------ kernel: 5.1.0 git repo: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git git branch: master git commit: 04c4b6775d34f12f196e056debed9e8718585342 git describe: next-20190513 Test details: https://qa-reports.linaro.org/lkft/linux-next-oe/build/next-20190513 Regressions (compared to build next-20190510) ------------------------------------------------------------------------ No regressions Fixes (compared to build next-20190510) ------------------------------------------------------------------------ No fixes In total: ------------------------------------------------------------------------ Ran 12 total tests in the following environments and test suites. pass 11 fail 1 xfail 0 skip 0 Environments -------------- - dragonboard-410c - arm64 - hi6220-hikey - arm64 - i386 - juno-r2 - arm64 - qemu_arm - qemu_arm64 - qemu_i386 - qemu_x86_64 - x15 - arm - x86_64 Test Suites ----------- * boot-lkft-kselftests-master-520 * boot-lkft-kselftests-vsyscall-mode-native-master-520 * boot-lkft-kselftests-vsyscall-mode-none-master-520 Failures ------------------------------------------------------------------------ qemu_i386: juno-r2: qemu_arm64: qemu_x86_64: hi6220-hikey: dragonboard-410c: * boot-lkft-kselftests-master-520/dragonboard-410c i386: x86: qemu_arm: x15: Skips ------------------------------------------------------------------------ No skips -- Linaro LKFT https://lkft.linaro.org

6 years, 4 months

1
0
0 0

Re: [PATCH 2/4] x86/kprobes: Fix frame pointer annotations

by Josh Poimboeuf

On Wed, May 08, 2019 at 05:39:07PM +0200, Peter Zijlstra wrote: > On Wed, May 08, 2019 at 07:42:48AM -0500, Josh Poimboeuf wrote: > > On Wed, May 08, 2019 at 02:04:16PM +0200, Peter Zijlstra wrote: > > > > Do the x86_64 variants also want some ORC annotation? > > > > Maybe so. Though it looks like regs->ip isn't saved. The saved > > registers might need to be tweaked. I'll need to look into it. > > What all these sites do (and maybe we should look at unifying them > somehow) is turn a CALL frame (aka RET-IP) into an exception frame (aka > pt_regs). > > So regs->ip will be the return address (which is fixed up to be the CALL > address in the handler). But from what I can tell, trampoline_handler() hard-codes regs->ip to point to kretprobe_trampoline(), and the original return address is placed in regs->sp. Masami, is there a reason why regs->ip doesn't have the original return address and regs->sp doesn't have the original SP? I think that would help the unwinder understand things. -- Josh

6 years, 4 months

5
22
0 0

[PATCH v2] selftests: bpf: Add files generated after build to .gitignore

by Kelsey Skunberg

The following files are generated after building /selftests/bpf/ and should be added to .gitignore: - libbpf.pc - libbpf.so.* Signed-off-by: Kelsey Skunberg <skunberg.kelsey(a)gmail.com> --- Change since v1: - Add libbpf.so.* in replace of libbpf.so.0 and libbpf.so.0.0.3 - Update commit log to reflect file change tools/testing/selftests/bpf/.gitignore | 2 ++ 1 file changed, 2 insertions(+) diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore index 41e8a689aa77..a877803e4ba8 100644 --- a/tools/testing/selftests/bpf/.gitignore +++ b/tools/testing/selftests/bpf/.gitignore @@ -32,3 +32,5 @@ test_tcpnotify_user test_libbpf test_tcp_check_syncookie_user alu32 +libbpf.pc +libbpf.so.* -- 2.20.1

6 years, 4 months

2
1
0 0

Build-time tests?

by Joe Lawrence

Hello kbuild, kselftest, I've been working on a patchset which adds an additional build script to the toolchain when compiling livepatches. There are a few kernel section features in which this script does not yet support, but can detect and abort when it encounters. To test this detection, I've written a small set of kernel modules that require such sections. A few questions: Is build-testing out of scope for kernel selftests? For expediency, it was really easy to spin out new lib/livepatch kernel modules. Does kbuild support the notion of expected failure? In this case, the build script returns a non-zero error and the build stops. Am I trying to fit a square peg in a round hole? I could easily keep these build tests in a private branch, but could they exist in a different format somewhere else in the tree? Suggestions welcome, -- Joe

6 years, 4 months

2
1
0 0

[PATCH] selftests: bpf: Add files generated when compiled to .gitignore

by Kelsey Skunberg

The following files are generated when /selftests/bpf/ is compiled and should be added to .gitignore: - libbpf.pc - libbpf.so.0 - libbpf.so.0.0.3 Signed-off-by: Kelsey Skunberg <skunberg.kelsey(a)gmail.com> --- tools/testing/selftests/bpf/.gitignore | 3 +++ 1 file changed, 3 insertions(+) diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore index 41e8a689aa77..ceb11f98fe4f 100644 --- a/tools/testing/selftests/bpf/.gitignore +++ b/tools/testing/selftests/bpf/.gitignore @@ -32,3 +32,6 @@ test_tcpnotify_user test_libbpf test_tcp_check_syncookie_user alu32 +libbpf.pc +libbpf.so.0 +libbpf.so.0.0.3 -- 2.20.1

6 years, 4 months

2
2
0 0

[PATCH] selftests: kvm: Add files generated when compiled to .gitignore

by Kelsey Skunberg

The following files are generated in /selftests/kvm/ after compiling and should be added to /selftests/kvm/.gitignore: - /x86_64/hyperv_cpuid - /x86_64/smm_test Signed-off-by: Kelsey Skunberg <skunberg.kelsey(a)gmail.com> --- tools/testing/selftests/kvm/.gitignore | 2 ++ 1 file changed, 2 insertions(+) diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore index 2689d1ea6d7a..81e9cb775ab8 100644 --- a/tools/testing/selftests/kvm/.gitignore +++ b/tools/testing/selftests/kvm/.gitignore @@ -6,4 +6,6 @@ /x86_64/vmx_close_while_nested_test /x86_64/vmx_tsc_adjust_test /x86_64/state_test +/x86_64/hyperv_cpuid +/x86_64/smm_test /dirty_log_test -- 2.20.1

6 years, 4 months

1
0
0 0

[PATCH 0/3] kheaders fixes for -rc

by Joel Fernandes (Google)

Linus, Greg, Masahiro, Here are some simple fixes for the kheaders feature. Please consider these patches for an rc release. They are based on Linus's master branch. Thanks! Joel Fernandes (Google) (3): kheaders: Move from proc to sysfs kheaders: Do not regenerate archive if config is not changed kheaders: Make it depend on sysfs init/Kconfig | 17 +++++---- kernel/Makefile | 4 +-- kernel/{gen_ikh_data.sh => gen_kheaders.sh} | 17 ++++++--- kernel/kheaders.c | 40 +++++++++------------ 4 files changed, 38 insertions(+), 40 deletions(-) rename kernel/{gen_ikh_data.sh => gen_kheaders.sh} (82%) -- 2.21.0.1020.gf2820cf01a-goog

6 years, 4 months

4
6
0 0

2025

2024

2023

2022

2021

2020

2019

2018

2017

Linux-kselftest-mirror