path: root/mm/memory.c
diff options
authorHugh Dickins <hugh.dickins@tiscali.co.uk>2009-09-21 17:03:25 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-22 07:17:40 -0700
commitf3e8fccd06d27773186a0094371daf2d84c79469 (patch)
tree46e652e6ac3588a26c6d3e38ea10274eb3fc2ea8 /mm/memory.c
parentmm: remove unused GUP flags (diff)
mm: add get_dump_page
In preparation for the next patch, add a simple get_dump_page(addr) interface for the CONFIG_ELF_CORE dumpers to use, instead of calling get_user_pages() directly. They're not interested in errors: they just want to use holes as much as possible, to save space and make sure that the data is aligned where the headers said it would be. Oh, and don't use that horrid DUMP_SEEK(off) macro! Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Acked-by: Rik van Riel <riel@redhat.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to '')
1 files changed, 32 insertions, 1 deletions
diff --git a/mm/memory.c b/mm/memory.c
index 4b5200f5f35a..a8430ff13837 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1423,9 +1423,40 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas);
+ * get_dump_page() - pin user page in memory while writing it to core dump
+ * @addr: user address
+ *
+ * Returns struct page pointer of user page pinned for dump,
+ * to be freed afterwards by page_cache_release() or put_page().
+ *
+ * Returns NULL on any kind of failure - a hole must then be inserted into
+ * the corefile, to preserve alignment with its headers; and also returns
+ * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
+ * allowing a hole to be left in the corefile to save diskspace.
+ *
+ * Called without mmap_sem, but after all other threads have been killed.
+ */
+struct page *get_dump_page(unsigned long addr)
+ struct vm_area_struct *vma;
+ struct page *page;
+ if (__get_user_pages(current, current->mm, addr, 1,
+ GUP_FLAGS_FORCE, &page, &vma) < 1)
+ return NULL;
+ if (page == ZERO_PAGE(0)) {
+ page_cache_release(page);
+ return NULL;
+ }
+ flush_cache_page(vma, addr, page_to_pfn(page));
+ return page;
+#endif /* CONFIG_ELF_CORE */
pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
spinlock_t **ptl)