diff options
Diffstat (limited to 'mm/util.c')
| -rw-r--r-- | mm/util.c | 31 |
1 files changed, 19 insertions, 12 deletions
@@ -4,9 +4,11 @@ #include <linux/module.h> #include <linux/err.h> #include <linux/sched.h> -#include <linux/tracepoint.h> #include <asm/uaccess.h> +#define CREATE_TRACE_POINTS +#include <trace/events/kmem.h> + /** * kstrdup - allocate space for and copy an existing string * @s: the string to duplicate @@ -166,6 +168,10 @@ EXPORT_SYMBOL(krealloc); * * The memory of the object @p points to is zeroed before freed. * If @p is %NULL, kzfree() does nothing. + * + * Note: this function zeroes the whole allocated buffer which can be a good + * deal bigger than the requested buffer size passed to kmalloc(). So be + * careful when using this function in performance sensitive code. */ void kzfree(const void *p) { @@ -231,13 +237,21 @@ void arch_pick_mmap_layout(struct mm_struct *mm) * @pages: array that receives pointers to the pages pinned. * Should be at least nr_pages long. * - * Attempt to pin user pages in memory without taking mm->mmap_sem. - * If not successful, it will fall back to taking the lock and - * calling get_user_pages(). - * * Returns number of pages pinned. This may be fewer than the number * requested. If nr_pages is 0 or negative, returns 0. If no pages * were pinned, returns -errno. + * + * get_user_pages_fast provides equivalent functionality to get_user_pages, + * operating on current and current->mm, with force=0 and vma=NULL. However + * unlike get_user_pages, it must be called without mmap_sem held. + * + * get_user_pages_fast may take mmap_sem and page table locks, so no + * assumptions can be made about lack of locking. get_user_pages_fast is to be + * implemented in a way that is advantageous (vs get_user_pages()) when the + * user memory area is already faulted in and present in ptes. However if the + * pages have to be faulted in, it may turn out to be slightly slower so + * callers need to carefully consider what to use. On many architectures, + * get_user_pages_fast simply falls back to get_user_pages. */ int __attribute__((weak)) get_user_pages_fast(unsigned long start, int nr_pages, int write, struct page **pages) @@ -255,13 +269,6 @@ int __attribute__((weak)) get_user_pages_fast(unsigned long start, EXPORT_SYMBOL_GPL(get_user_pages_fast); /* Tracepoints definitions. */ -DEFINE_TRACE(kmalloc); -DEFINE_TRACE(kmem_cache_alloc); -DEFINE_TRACE(kmalloc_node); -DEFINE_TRACE(kmem_cache_alloc_node); -DEFINE_TRACE(kfree); -DEFINE_TRACE(kmem_cache_free); - EXPORT_TRACEPOINT_SYMBOL(kmalloc); EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc); EXPORT_TRACEPOINT_SYMBOL(kmalloc_node); |