diff options
| author | Heinrich Schuchardt <xypron.glpk@gmx.de> | 2015-04-16 12:47:44 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-04-17 09:04:06 -0400 |
| commit | ff691f6e03815dc8f99461ea509df863a879fc3a (patch) | |
| tree | acc3b3c61ff40365d15cbe89952c743b301016af | |
| parent | 3ea7f5e25ec271909451b7dc17be37581b888de6 (diff) | |
| download | linux-ff691f6e03815dc8f99461ea509df863a879fc3a.tar.bz2 | |
kernel/fork.c: new function for max_threads
PAGE_SIZE is not guaranteed to be equal to or less than 8 times the
THREAD_SIZE.
E.g. architecture hexagon may have page size 1M and thread size 4096.
This would lead to a division by zero in the calculation of max_threads.
With this patch the buggy code is moved to a separate function
set_max_threads. The error is not fixed.
After fixing the problem in a separate patch the new function can be
reused to adjust max_threads after adding or removing memory.
Argument mempages of function fork_init() is removed as totalram_pages is
an exported symbol.
The creation of separate patches for refactoring to a new function and for
fixing the logic was suggested by Ingo Molnar.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | init/main.c | 4 | ||||
| -rw-r--r-- | kernel/fork.c | 34 |
2 files changed, 23 insertions, 15 deletions
diff --git a/init/main.c b/init/main.c index a7e969d12f51..2115055faeac 100644 --- a/init/main.c +++ b/init/main.c @@ -91,7 +91,7 @@ static int kernel_init(void *); extern void init_IRQ(void); -extern void fork_init(unsigned long); +extern void fork_init(void); extern void radix_tree_init(void); #ifndef CONFIG_DEBUG_RODATA static inline void mark_rodata_ro(void) { } @@ -645,7 +645,7 @@ asmlinkage __visible void __init start_kernel(void) #endif thread_info_cache_init(); cred_init(); - fork_init(totalram_pages); + fork_init(); proc_caches_init(); buffer_init(); key_init(); diff --git a/kernel/fork.c b/kernel/fork.c index c507e29bcb01..01038e6f51a8 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -253,7 +253,26 @@ EXPORT_SYMBOL_GPL(__put_task_struct); void __init __weak arch_task_cache_init(void) { } -void __init fork_init(unsigned long mempages) +/* + * set_max_threads + */ +static void set_max_threads(void) +{ + /* + * The default maximum number of threads is set to a safe + * value: the thread structures can take up at most one + * eighth of the memory. + */ + max_threads = totalram_pages / (8 * THREAD_SIZE / PAGE_SIZE); + + /* + * we need to allow at least 20 threads to boot a system + */ + if (max_threads < 20) + max_threads = 20; +} + +void __init fork_init(void) { #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR #ifndef ARCH_MIN_TASKALIGN @@ -268,18 +287,7 @@ void __init fork_init(unsigned long mempages) /* do the arch specific task caches init */ arch_task_cache_init(); - /* - * The default maximum number of threads is set to a safe - * value: the thread structures can take up at most one - * eighth of the memory. - */ - max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE); - - /* - * we need to allow at least 20 threads to boot a system - */ - if (max_threads < 20) - max_threads = 20; + set_max_threads(); init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2; init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2; |