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Commit a68d2ebc authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Fix up recent get_user_pages() handling 



The VM_FAULT_WRITE thing is an extra bit, not a valid return value, and
has to be treated as such by get_user_pages().

Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent f33ea7f4

mm/memory.c

+13 −9
Original line number Diff line number Diff line
@@ -949,6 +949,8 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 


			cond_resched_lock(&mm->page_table_lock);

			while (!(page = follow_page(mm, start, write_access))) {

				int ret;



				/*

				 * Shortcut for anonymous pages. We don't want

				 * to force the creation of pages tables for
@@ -961,16 +963,18 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 
					break;

				}

				spin_unlock(&mm->page_table_lock);

				switch (__handle_mm_fault(mm, vma, start,

							write_access)) {

				case VM_FAULT_WRITE:

				ret = __handle_mm_fault(mm, vma, start, write_access);



				/*

					 * do_wp_page has broken COW when

					 * necessary, even if maybe_mkwrite

					 * decided not to set pte_write

				 * The VM_FAULT_WRITE bit tells us that do_wp_page has

				 * broken COW when necessary, even if maybe_mkwrite

				 * decided not to set pte_write. We can thus safely do

				 * subsequent page lookups as if they were reads.

				 */

				if (ret & VM_FAULT_WRITE)

					write_access = 0;

					/* FALLTHRU */

				

				switch (ret & ~VM_FAULT_WRITE) {

				case VM_FAULT_MINOR:

					tsk->min_flt++;

					break;