| Message ID | 1486808828-8854-1-git-send-email-hoeun.ryu@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Hoeun,
[auto build test ERROR on linus/master]
[also build test ERROR on v4.10-rc7 next-20170210]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Hoeun-Ryu/fork-free-vmapped-stacks-in-cache-when-cpus-are-offline/20170211-183401
config: ia64-allmodconfig (attached as .config)
compiler: ia64-linux-gcc (GCC) 6.2.0
reproduce:
wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
make.cross ARCH=ia64
All errors (new ones prefixed by >>):
kernel/fork.c: In function 'fork_init':
>> kernel/fork.c:483:2: error: implicit declaration of function 'vm_stack_cache_init' [-Werror=implicit-function-declaration]
vm_stack_cache_init();
^~~~~~~~~~~~~~~~~~~
cc1: some warnings being treated as errors
vim +/vm_stack_cache_init +483 kernel/fork.c
477 init_task.signal->rlim[RLIMIT_NPROC];
478
479 for (i = 0; i < UCOUNT_COUNTS; i++) {
480 init_user_ns.ucount_max[i] = max_threads/2;
481 }
482
> 483 vm_stack_cache_init();
484 }
485
486 int __weak arch_dup_task_struct(struct task_struct *dst,
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
On Sat, 11 Feb 2017, kbuild test robot wrote: > Hi Hoeun, > > [auto build test ERROR on linus/master] > [also build test ERROR on v4.10-rc7 next-20170210] > [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] > > url: https://github.com/0day-ci/linux/commits/Hoeun-Ryu/fork-free-vmapped-stacks-in-cache-when-cpus-are-offline/20170211-183401 > config: ia64-allmodconfig (attached as .config) > compiler: ia64-linux-gcc (GCC) 6.2.0 > reproduce: > wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross > chmod +x ~/bin/make.cross > # save the attached .config to linux build tree > make.cross ARCH=ia64 > > All errors (new ones prefixed by >>): > > kernel/fork.c: In function 'fork_init': > >> kernel/fork.c:483:2: error: implicit declaration of function 'vm_stack_cache_init' [-Werror=implicit-function-declaration] > vm_stack_cache_init(); > ^~~~~~~~~~~~~~~~~~~ Right. This needs to move to a different place as that part is nested inside #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR That's an horrible ifdef maze in that file. Thanks, tglx
> On Feb 12, 2017, at 5:19 AM, Thomas Gleixner <tglx@linutronix.de> wrote: > >> On Sat, 11 Feb 2017, kbuild test robot wrote: >> >> Hi Hoeun, >> >> [auto build test ERROR on linus/master] >> [also build test ERROR on v4.10-rc7 next-20170210] >> [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] >> >> url: https://github.com/0day-ci/linux/commits/Hoeun-Ryu/fork-free-vmapped-stacks-in-cache-when-cpus-are-offline/20170211-183401 >> config: ia64-allmodconfig (attached as .config) >> compiler: ia64-linux-gcc (GCC) 6.2.0 >> reproduce: >> wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross >> chmod +x ~/bin/make.cross >> # save the attached .config to linux build tree >> make.cross ARCH=ia64 >> >> All errors (new ones prefixed by >>): >> >> kernel/fork.c: In function 'fork_init': >>>> kernel/fork.c:483:2: error: implicit declaration of function 'vm_stack_cache_init' [-Werror=implicit-function-declaration] >> vm_stack_cache_init(); >> ^~~~~~~~~~~~~~~~~~~ > > Right. This needs to move to a different place as that part is nested inside > > #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR > > That's an horrible ifdef maze in that file. > I think we should rollback to v4. Do you agree? > Thanks, > > tglx
On Sun, 12 Feb 2017, Hoeun Ryu wrote: > > > On Feb 12, 2017, at 5:19 AM, Thomas Gleixner <tglx@linutronix.de> wrote: > > > >> On Sat, 11 Feb 2017, kbuild test robot wrote: > >> > >> Hi Hoeun, > >> > >> [auto build test ERROR on linus/master] > >> [also build test ERROR on v4.10-rc7 next-20170210] > >> [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] > >> > >> url: https://github.com/0day-ci/linux/commits/Hoeun-Ryu/fork-free-vmapped-stacks-in-cache-when-cpus-are-offline/20170211-183401 > >> config: ia64-allmodconfig (attached as .config) > >> compiler: ia64-linux-gcc (GCC) 6.2.0 > >> reproduce: > >> wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross > >> chmod +x ~/bin/make.cross > >> # save the attached .config to linux build tree > >> make.cross ARCH=ia64 > >> > >> All errors (new ones prefixed by >>): > >> > >> kernel/fork.c: In function 'fork_init': > >>>> kernel/fork.c:483:2: error: implicit declaration of function 'vm_stack_cache_init' [-Werror=implicit-function-declaration] > >> vm_stack_cache_init(); > >> ^~~~~~~~~~~~~~~~~~~ > > > > Right. This needs to move to a different place as that part is nested inside > > > > #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR > > > > That's an horrible ifdef maze in that file. > > > > I think we should rollback to v4. Do you agree? Sigh. Yes.
diff --git a/kernel/fork.c b/kernel/fork.c index 937ba59..86a1110 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -168,6 +168,32 @@ void __weak arch_release_thread_stack(unsigned long *stack) */ #define NR_CACHED_STACKS 2 static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]); + +static int __maybe_unused free_vm_stack_cache(unsigned int cpu) +{ + struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu); + int i; + + for (i = 0; i < NR_CACHED_STACKS; i++) { + struct vm_struct *vm_stack = cached_vm_stacks[i]; + + if (!vm_stack) + continue; + + vfree(vm_stack->addr); + cached_vm_stacks[i] = NULL; + } + + return 0; +} + +static inline int vm_stack_cache_init(void) +{ + return cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache", + NULL, free_vm_stack_cache); +} +#else +static __always_inline int vm_stack_cache_init(void) { return 0; } #endif static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node) @@ -456,6 +482,8 @@ void __init fork_init(void) for (i = 0; i < UCOUNT_COUNTS; i++) { init_user_ns.ucount_max[i] = max_threads/2; } + + vm_stack_cache_init(); } int __weak arch_dup_task_struct(struct task_struct *dst,
Using virtually mapped stack, kernel stacks are allocated via vmalloc. In the current implementation, two stacks per cpu can be cached when tasks are freed and the cached stacks are used again in task duplications. but the cached stacks may remain unfreed even when cpus are offline. By adding a cpu hotplug callback to free the cached stacks when a cpu goes offline, the pages of the cached stacks are not wasted. Signed-off-by: Hoeun Ryu <hoeun.ryu@gmail.com> --- v5: - wrap cpuhp_setup_state() in a new function, vm_stack_cache_init() which actually do nothing when !CONFIG_VMAP_STACK - add __may_unused to free_vm_stack_cache() v4: - use CPUHP_BP_PREPARE_DYN state for cpuhp setup - fix minor coding style v3: - fix misuse of per-cpu api - fix location of function definition within CONFIG_VMAP_STACK v2: - remove cpuhp callback for `startup`, only `teardown` callback is installed. kernel/fork.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+)