mm/page_io.c: fix oops during block io poll in swapin path

[sfrench/cifs-2.6.git] / mm / page_io.c

diff --git a/mm/page_io.c b/mm/page_io.c
index b6c4ac388209c945d744f2541326411314a1cceb..5f61b54ee1f38e0bb7ae7bee3efe3257f8967a44 100644 (file)
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -22,6 +22,7 @@
 #include <linux/frontswap.h>
 #include <linux/blkdev.h>
 #include <linux/uio.h>
+#include <linux/sched/task.h>
 #include <asm/pgtable.h>
 
 static struct bio *get_swap_bio(gfp_t gfp_flags,
@@ -136,6 +137,7 @@ out:
        WRITE_ONCE(bio->bi_private, NULL);
        bio_put(bio);
        wake_up_process(waiter);
+       put_task_struct(waiter);
 }
 
 int generic_swapfile_activate(struct swap_info_struct *sis,
@@ -378,6 +380,11 @@ int swap_readpage(struct page *page, bool do_poll)
                goto out;
        }
        bdev = bio->bi_bdev;
+       /*
+        * Keep this task valid during swap readpage because the oom killer may
+        * attempt to access it in the page fault retry time check.
+        */
+       get_task_struct(current);
        bio->bi_private = current;
        bio_set_op_attrs(bio, REQ_OP_READ, 0);
        count_vm_event(PSWPIN);