[PATCH] fix page leak during core dump

When the dump cannot occur most likely because of a full file system and
the page to be written is the zero page, the call to page_cache_release()
is missed.
Signed-off-by: Brian Pomerantz <bapper@mvista.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: David Howells <dhowells@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/binfmt_elf.c

@@ -1704,7 +1704,10 @@ static int elf_core_dump(long signr, struct pt_regs *regs, struct file *file)
 				DUMP_SEEK(PAGE_SIZE);
 			} else {
 				if (page == ZERO_PAGE(addr)) {
-					DUMP_SEEK(PAGE_SIZE);
+					if (!dump_seek(file, PAGE_SIZE)) {
+						page_cache_release(page);
+						goto end_coredump;
+					}
 				} else {
 					void *kaddr;
 					flush_cache_page(vma, addr,

fs/binfmt_elf_fdpic.c

@@ -1480,8 +1480,8 @@ static int elf_fdpic_dump_segments(struct file *file, struct mm_struct *mm,
 				DUMP_SEEK(file->f_pos + PAGE_SIZE);
 			}
 			else if (page == ZERO_PAGE(addr)) {
-				DUMP_SEEK(file->f_pos + PAGE_SIZE);
 				page_cache_release(page);
+				DUMP_SEEK(file->f_pos + PAGE_SIZE);
 			}
 			else {
 				void *kaddr;