delayacct: clear right task's flag after blkio completes

When I was implementing a latency analyzer tool by using task->delays
and other things, I found an issue in delayacct.  The issue is it should
clear the target's flag instead of current's in delayacct_blkio_end().

When I git blame delayacct, I found there're some similar issues we have
fixed in delayacct_blkio_end().

 - Commit c96f5471ce7d ("delayacct: Account blkio completion on the
   correct task") fixed the issue that it should account blkio
   completion on the target task instead of current.

 - Commit b512719f771a ("delayacct: fix crash in delayacct_blkio_end()
   after delayacct init failure") fixed the issue that it should check
   target task's delays instead of current task'.

It seems that delayacct_blkio_{begin, end} are error prone.

So I introduce a new paratmeter - the target task 'p' - to these
helpers.  After that change, the callsite will specifilly set the right
task, which should make it less error prone.

Link: https://lkml.kernel.org/r/20210414083720.24083-1-laoar.shao@gmail.com
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Josh Snyder <joshs@netflix.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/mm/memory.c b/mm/memory.c
index cbdc2cd9cedb..8c491f813687 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3339,7 +3339,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 	}
 
 
-	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
+	delayacct_set_flag(current, DELAYACCT_PF_SWAPIN);
 	page = lookup_swap_cache(entry, vma, vmf->address);
 	swapcache = page;
 
@@ -3388,7 +3388,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 					vmf->address, &vmf->ptl);
 			if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
 				ret = VM_FAULT_OOM;
-			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
+			delayacct_clear_flag(current, DELAYACCT_PF_SWAPIN);
 			goto unlock;
 		}
 
@@ -3402,13 +3402,13 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 		 * owner processes (which may be unknown at hwpoison time)
 		 */
 		ret = VM_FAULT_HWPOISON;
-		delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
+		delayacct_clear_flag(current, DELAYACCT_PF_SWAPIN);
 		goto out_release;
 	}
 
 	locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);
 
-	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
+	delayacct_clear_flag(current, DELAYACCT_PF_SWAPIN);
 	if (!locked) {
 		ret |= VM_FAULT_RETRY;
 		goto out_release;