The patch titled Subject: ptrace: revert "Prepare to fix racy accesses on task breakpoints" has been added to the -mm tree. Its filename is ptrace-revert-prepare-to-fix-racy-accesses-on-task-breakpoints.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Oleg Nesterov <oleg@xxxxxxxxxx> Subject: ptrace: revert "Prepare to fix racy accesses on task breakpoints" This reverts commit bf26c018490c2fce ("Prepare to fix racy accesses on task breakpoints"). The patch was fine but we can no longer race with SIGKILL after 9899d11f ("ptrace: ensure arch_ptrace/ptrace_request can never race with SIGKILL"), the __TASK_TRACED tracee can't be woken up and ->ptrace_bps[] can't go away. Now that ptrace_get_breakpoints/ptrace_put_breakpoints have no callers, we can kill them and remove task->ptrace_bp_refcnt. Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> Acked-by: Frederic Weisbecker <fweisbec@xxxxxxxxx> Acked-by: Michael Neuling <mikey@xxxxxxxxxxx> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Jan Kratochvil <jan.kratochvil@xxxxxxxxxx> Cc: Paul Mackerras <paulus@xxxxxxxxx> Cc: Paul Mundt <lethal@xxxxxxxxxxxx> Cc: Will Deacon <will.deacon@xxxxxxx> Cc: Prasad <prasad@xxxxxxxxxxxxxxxxxx> Cc: Russell King <linux@xxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/ptrace.h | 10 ---------- include/linux/sched.h | 3 --- kernel/exit.c | 2 +- kernel/ptrace.c | 16 ---------------- 4 files changed, 1 insertion(+), 30 deletions(-) diff -puN include/linux/ptrace.h~ptrace-revert-prepare-to-fix-racy-accesses-on-task-breakpoints include/linux/ptrace.h --- a/include/linux/ptrace.h~ptrace-revert-prepare-to-fix-racy-accesses-on-task-breakpoints +++ a/include/linux/ptrace.h @@ -142,9 +142,6 @@ static inline void ptrace_init_task(stru { INIT_LIST_HEAD(&child->ptrace_entry); INIT_LIST_HEAD(&child->ptraced); -#ifdef CONFIG_HAVE_HW_BREAKPOINT - atomic_set(&child->ptrace_bp_refcnt, 1); -#endif child->jobctl = 0; child->ptrace = 0; child->parent = child->real_parent; @@ -351,11 +348,4 @@ extern int task_current_syscall(struct t unsigned long args[6], unsigned int maxargs, unsigned long *sp, unsigned long *pc); -#ifdef CONFIG_HAVE_HW_BREAKPOINT -extern int ptrace_get_breakpoints(struct task_struct *tsk); -extern void ptrace_put_breakpoints(struct task_struct *tsk); -#else -static inline void ptrace_put_breakpoints(struct task_struct *tsk) { } -#endif /* CONFIG_HAVE_HW_BREAKPOINT */ - #endif diff -puN include/linux/sched.h~ptrace-revert-prepare-to-fix-racy-accesses-on-task-breakpoints include/linux/sched.h --- a/include/linux/sched.h~ptrace-revert-prepare-to-fix-racy-accesses-on-task-breakpoints +++ a/include/linux/sched.h @@ -1404,9 +1404,6 @@ struct task_struct { } memcg_batch; unsigned int memcg_kmem_skip_account; #endif -#ifdef CONFIG_HAVE_HW_BREAKPOINT - atomic_t ptrace_bp_refcnt; -#endif #ifdef CONFIG_UPROBES struct uprobe_task *utask; #endif diff -puN kernel/exit.c~ptrace-revert-prepare-to-fix-racy-accesses-on-task-breakpoints kernel/exit.c --- a/kernel/exit.c~ptrace-revert-prepare-to-fix-racy-accesses-on-task-breakpoints +++ a/kernel/exit.c @@ -819,7 +819,7 @@ void do_exit(long code) /* * FIXME: do that only when needed, using sched_exit tracepoint */ - ptrace_put_breakpoints(tsk); + flush_ptrace_hw_breakpoint(tsk); exit_notify(tsk, group_dead); #ifdef CONFIG_NUMA diff -puN kernel/ptrace.c~ptrace-revert-prepare-to-fix-racy-accesses-on-task-breakpoints kernel/ptrace.c --- a/kernel/ptrace.c~ptrace-revert-prepare-to-fix-racy-accesses-on-task-breakpoints +++ a/kernel/ptrace.c @@ -1179,19 +1179,3 @@ asmlinkage long compat_sys_ptrace(compat return ret; } #endif /* CONFIG_COMPAT */ - -#ifdef CONFIG_HAVE_HW_BREAKPOINT -int ptrace_get_breakpoints(struct task_struct *tsk) -{ - if (atomic_inc_not_zero(&tsk->ptrace_bp_refcnt)) - return 0; - - return -1; -} - -void ptrace_put_breakpoints(struct task_struct *tsk) -{ - if (atomic_dec_and_test(&tsk->ptrace_bp_refcnt)) - flush_ptrace_hw_breakpoint(tsk); -} -#endif /* CONFIG_HAVE_HW_BREAKPOINT */ _ Patches currently in -mm which might be from oleg@xxxxxxxxxx are posix_cpu_timer-consolidate-expiry-time-type.patch posix_cpu_timers-consolidate-timer-list-cleanups.patch posix_cpu_timers-consolidate-expired-timers-check.patch posix-timers-correctly-get-dying-task-time-sample-in-posix_cpu_timer_schedule.patch posix_timers-fix-racy-timer-delta-caching-on-task-exit.patch lockdep-introduce-lock_acquire_exclusive-shared-helper-macros.patch lglock-update-lockdep-annotations-to-report-recursive-local-locks.patch autofs4-allow-autofs-to-work-outside-the-initial-pid-namespace.patch autofs4-translate-pids-to-the-right-namespace-for-the-daemon.patch ptrace-x86-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch ptrace-powerpc-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch ptrace-arm-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch ptrace-sh-revert-hw_breakpoints-fix-racy-access-to-ptrace-breakpoints.patch ptrace-revert-prepare-to-fix-racy-accesses-on-task-breakpoints.patch ptrace-x86-simplify-the-disable-logic-in-ptrace_write_dr7.patch ptrace-x86-dont-delay-disable-till-second-pass-in-ptrace_write_dr7.patch ptrace-x86-introduce-ptrace_register_breakpoint.patch ptrace-x86-ptrace_write_dr7-should-create-bp-if-disabled.patch ptrace-x86-cleanup-ptrace_set_debugreg.patch ptrace-ptrace_detach-should-do-flush_ptrace_hw_breakpointchild.patch ptrace-x86-flush_ptrace_hw_breakpoint-shoule-clear-the-virtual-debug-registers.patch x86-kill-tif_debug.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html