linux/kernel/exit.c, branch v5.7

proc: Put thread_pid in release_task not proc_flush_pid

2020-04-24T20:49:00Z

Oleg pointed out that in the unlikely event the kernel is compiled with CONFIG_PROC_FS unset that release_task will now leak the pid. Move the put_pid out of proc_flush_pid into release_task to fix this and to guarantee I don't make that mistake again. When possible it makes sense to keep get and put in the same function so it can easily been seen how they pair up. Fixes: 7bc3e6e55acf ("proc: Use a list of inodes to flush from proc") Reported-by: Oleg Nesterov Signed-off-by: "Eric W. Biederman"

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

2020-04-02T18:22:17Z

Pull exec/proc updates from Eric Biederman: "This contains two significant pieces of work: the work to sort out proc_flush_task, and the work to solve a deadlock between strace and exec. Fixing proc_flush_task so that it no longer requires a persistent mount makes improvements to proc possible. The removal of the persistent mount solves an old regression that that caused the hidepid mount option to only work on remount not on mount. The regression was found and reported by the Android folks. This further allows Alexey Gladkov's work making proc mount options specific to an individual mount of proc to move forward. The work on exec starts solving a long standing issue with exec that it takes mutexes of blocking userspace applications, which makes exec extremely deadlock prone. For the moment this adds a second mutex with a narrower scope that handles all of the easy cases. Which makes the tricky cases easy to spot. With a little luck the code to solve those deadlocks will be ready by next merge window" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (25 commits) signal: Extend exec_id to 64bits pidfd: Use new infrastructure to fix deadlocks in execve perf: Use new infrastructure to fix deadlocks in execve proc: io_accounting: Use new infrastructure to fix deadlocks in execve proc: Use new infrastructure to fix deadlocks in execve kernel/kcmp.c: Use new infrastructure to fix deadlocks in execve kernel: doc: remove outdated comment cred.c mm: docs: Fix a comment in process_vm_rw_core selftests/ptrace: add test cases for dead-locks exec: Fix a deadlock in strace exec: Add exec_update_mutex to replace cred_guard_mutex exec: Move exec_mmap right after de_thread in flush_old_exec exec: Move cleanup of posix timers on exec out of de_thread exec: Factor unshare_sighand out of de_thread and call it separately exec: Only compute current once in flush_old_exec pid: Improve the comment about waiting in zap_pid_ns_processes proc: Remove the now unnecessary internal mount of proc uml: Create a private mount of proc for mconsole uml: Don't consult current to find the proc_mnt in mconsole_proc proc: Use a list of inodes to flush from proc ...

Merge tag 'timers-core-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-03-31T01:51:47Z

Pull timekeeping and timer updates from Thomas Gleixner: "Core: - Consolidation of the vDSO build infrastructure to address the difficulties of cross-builds for ARM64 compat vDSO libraries by restricting the exposure of header content to the vDSO build. This is achieved by splitting out header content into separate headers. which contain only the minimaly required information which is necessary to build the vDSO. These new headers are included from the kernel headers and the vDSO specific files. - Enhancements to the generic vDSO library allowing more fine grained control over the compiled in code, further reducing architecture specific storage and preparing for adopting the generic library by PPC. - Cleanup and consolidation of the exit related code in posix CPU timers. - Small cleanups and enhancements here and there Drivers: - The obligatory new drivers: Ingenic JZ47xx and X1000 TCU support - Correct the clock rate of PIT64b global clock - setup_irq() cleanup - Preparation for PWM and suspend support for the TI DM timer - Expand the fttmr010 driver to support ast2600 systems - The usual small fixes, enhancements and cleanups all over the place" * tag 'timers-core-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (80 commits) Revert "clocksource/drivers/timer-probe: Avoid creating dead devices" vdso: Fix clocksource.h macro detection um: Fix header inclusion arm64: vdso32: Enable Clang Compilation lib/vdso: Enable common headers arm: vdso: Enable arm to use common headers x86/vdso: Enable x86 to use common headers mips: vdso: Enable mips to use common headers arm64: vdso32: Include common headers in the vdso library arm64: vdso: Include common headers in the vdso library arm64: Introduce asm/vdso/processor.h arm64: vdso32: Code clean up linux/elfnote.h: Replace elf.h with UAPI equivalent scripts: Fix the inclusion order in modpost common: Introduce processor.h linux/ktime.h: Extract common header for vDSO linux/jiffies.h: Extract common header for vDSO linux/time64.h: Extract common header for vDSO linux/time32.h: Extract common header for vDSO linux/time.h: Extract common header for vDSO ...

Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-03-30T23:17:15Z

Pull locking updates from Ingo Molnar: "The main changes in this cycle were: - Continued user-access cleanups in the futex code. - percpu-rwsem rewrite that uses its own waitqueue and atomic_t instead of an embedded rwsem. This addresses a couple of weaknesses, but the primary motivation was complications on the -rt kernel. - Introduce raw lock nesting detection on lockdep (CONFIG_PROVE_RAW_LOCK_NESTING=y), document the raw_lock vs. normal lock differences. This too originates from -rt. - Reuse lockdep zapped chain_hlocks entries, to conserve RAM footprint on distro-ish kernels running into the "BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!" depletion of the lockdep chain-entries pool. - Misc cleanups, smaller fixes and enhancements - see the changelog for details" * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (55 commits) fs/buffer: Make BH_Uptodate_Lock bit_spin_lock a regular spinlock_t thermal/x86_pkg_temp: Make pkg_temp_lock a raw_spinlock_t Documentation/locking/locktypes: Minor copy editor fixes Documentation/locking/locktypes: Further clarifications and wordsmithing m68knommu: Remove mm.h include from uaccess_no.h x86: get rid of user_atomic_cmpxchg_inatomic() generic arch_futex_atomic_op_inuser() doesn't need access_ok() x86: don't reload after cmpxchg in unsafe_atomic_op2() loop x86: convert arch_futex_atomic_op_inuser() to user_access_begin/user_access_end() objtool: whitelist __sanitizer_cov_trace_switch() [parisc, s390, sparc64] no need for access_ok() in futex handling sh: no need of access_ok() in arch_futex_atomic_op_inuser() futex: arch_futex_atomic_op_inuser() calling conventions change completion: Use lockdep_assert_RT_in_threaded_ctx() in complete_all() lockdep: Add posixtimer context tracing bits lockdep: Annotate irq_work lockdep: Add hrtimer context tracing bits lockdep: Introduce wait-type checks completion: Use simple wait queues sched/swait: Prepare usage in completions ...

posix-cpu-timers: Stop disabling timers on mt-exec

2020-03-04T08:54:55Z

The reasons why the extra posix_cpu_timers_exit_group() invocation has been added are not entirely clear from the commit message. Today all that posix_cpu_timers_exit_group() does is stop timers that are tracking the task from firing. Every other operation on those timers is still allowed. The practical implication of this is posix_cpu_timer_del() which could not get the siglock after the thread group leader has exited (because sighand == NULL) would be able to run successfully because the timer was already dequeued. With that locking issue fixed there is no point in disabling all of the timers. So remove this ``tempoary'' hack. Fixes: e0a70217107e ("posix-cpu-timers: workaround to suppress the problems with mt exec") Signed-off-by: "Eric W. Biederman" Signed-off-by: Thomas Gleixner Link: https://lkml.kernel.org/r/87o8tityzs.fsf@x220.int.ebiederm.org

exit: Fix Sparse errors and warnings

2020-02-28T12:34:39Z

This patch fixes the following sparse error: kernel/exit.c:627:25: error: incompatible types in comparison expression And the following warning: kernel/exit.c:626:40: warning: incorrect type in assignment Signed-off-by: Madhuparna Bhowmik Acked-by: Oleg Nesterov Acked-by: Christian Brauner [christian.brauner@ubuntu.com: edit commit message] Link: https://lore.kernel.org/r/20200130062028.4870-1-madhuparnabhowmik10@gmail.com Signed-off-by: Christian Brauner

proc: Use a list of inodes to flush from proc

2020-02-24T16:14:44Z

Rework the flushing of proc to use a list of directory inodes that need to be flushed. The list is kept on struct pid not on struct task_struct, as there is a fixed connection between proc inodes and pids but at least for the case of de_thread the pid of a task_struct changes. This removes the dependency on proc_mnt which allows for different mounts of proc having different mount options even in the same pid namespace and this allows for the removal of proc_mnt which will trivially the first mount of proc to honor it's mount options. This flushing remains an optimization. The functions pid_delete_dentry and pid_revalidate ensure that ordinary dcache management will not attempt to use dentries past the point their respective task has died. When unused the shrinker will eventually be able to remove these dentries. There is a case in de_thread where proc_flush_pid can be called early for a given pid. Which winds up being safe (if suboptimal) as this is just an optiimization. Only pid directories are put on the list as the other per pid files are children of those directories and d_invalidate on the directory will get them as well. So that the pid can be used during flushing it's reference count is taken in release_task and dropped in proc_flush_pid. Further the call of proc_flush_pid is moved after the tasklist_lock is released in release_task so that it is certain that the pid has already been unhashed when flushing it taking place. This removes a small race where a dentry could recreated. As struct pid is supposed to be small and I need a per pid lock I reuse the only lock that currently exists in struct pid the the wait_pidfd.lock. The net result is that this adds all of this functionality with just a little extra list management overhead and a single extra pointer in struct pid. v2: Initialize pid->inodes. I somehow failed to get that initialization into the initial version of the patch. A boot failure was reported by "kernel test robot ", and failure to initialize that pid->inodes matches all of the reported symptoms. Signed-off-by: Eric W. Biederman

locking/percpu-rwsem: Fold __percpu_up_read()

2020-02-11T12:10:58Z

Now that __percpu_up_read() is only ever used from percpu_up_read() merge them, it's a small function. Signed-off-by: Davidlohr Bueso Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Acked-by: Will Deacon Acked-by: Waiman Long Link: https://lkml.kernel.org/r/20200131151540.212415454@infradead.org

Merge tag 'for-linus-2020-01-03' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

2020-01-03T19:17:14Z

Pull thread fixes from Christian Brauner: "Here are two fixes: - Panic earlier when global init exits to generate useable coredumps. Currently, when global init and all threads in its thread-group have exited we panic via: do_exit() -> exit_notify() -> forget_original_parent() -> find_child_reaper() This makes it hard to extract a useable coredump for global init from a kernel crashdump because by the time we panic exit_mm() will have already released global init's mm. We now panic slightly earlier. This has been a problem in certain environments such as Android. - Fix a race in assigning and reading taskstats for thread-groups with more than one thread. This patch has been waiting for quite a while since people disagreed on what the correct fix was at first" * tag 'for-linus-2020-01-03' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: exit: panic before exit_mm() on global init exit taskstats: fix data-race

exit: panic before exit_mm() on global init exit

2019-12-21T15:48:01Z

Currently, when global init and all threads in its thread-group have exited we panic via: do_exit() -> exit_notify() -> forget_original_parent() -> find_child_reaper() This makes it hard to extract a useable coredump for global init from a kernel crashdump because by the time we panic exit_mm() will have already released global init's mm. This patch moves the panic futher up before exit_mm() is called. As was the case previously, we only panic when global init and all its threads in the thread-group have exited. Signed-off-by: chenqiwu Acked-by: Christian Brauner Acked-by: Oleg Nesterov [christian.brauner@ubuntu.com: fix typo, rewrite commit message] Link: https://lore.kernel.org/r/1576736993-10121-1-git-send-email-qiwuchen55@gmail.com Signed-off-by: Christian Brauner