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From: Hugh Dickins <hughd@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
	 "Alex Xu (Hello71)" <alex_y_xu@yahoo.ca>,
	 Vineeth Pillai <vpillai@digitalocean.com>,
	 Kelley Nielsen <kelleynnn@gmail.com>,
	Rik van Riel <riel@surriel.com>,
	 Huang Ying <ying.huang@intel.com>,
	Hugh Dickins <hughd@google.com>,
	 linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH 3/4] mm: swapoff: take notice of completion sooner
Date: Mon, 8 Apr 2019 12:59:32 -0700 (PDT)
Message-ID: <alpine.LSU.2.11.1904081258200.1523@eggly.anvils> (raw)
In-Reply-To: <alpine.LSU.2.11.1904081249370.1523@eggly.anvils>

The old try_to_unuse() implementation was driven by find_next_to_unuse(),
which terminated as soon as all the swap had been freed.  Add inuse_pages
checks now (alongside signal_pending()) to stop scanning mms and swap_map
once finished.  The same ought to be done in shmem_unuse() too, but never
was before, and needs a different interface: so leave it as is for now.

Fixes: b56a2d8af914 ("mm: rid swapoff of quadratic complexity")
Signed-off-by: Hugh Dickins <hughd@google.com>
---

 mm/swapfile.c |   19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

--- 5.1-rc4/mm/swapfile.c	2019-04-07 19:15:01.269054187 -0700
+++ linux/mm/swapfile.c	2019-04-07 19:17:13.291957539 -0700
@@ -2051,11 +2051,9 @@ retry:
 
 	spin_lock(&mmlist_lock);
 	p = &init_mm.mmlist;
-	while ((p = p->next) != &init_mm.mmlist) {
-		if (signal_pending(current)) {
-			retval = -EINTR;
-			break;
-		}
+	while (si->inuse_pages &&
+	       !signal_pending(current) &&
+	       (p = p->next) != &init_mm.mmlist) {
 
 		mm = list_entry(p, struct mm_struct, mmlist);
 		if (!mmget_not_zero(mm))
@@ -2082,7 +2080,9 @@ retry:
 	mmput(prev_mm);
 
 	i = 0;
-	while ((i = find_next_to_unuse(si, i, frontswap)) != 0) {
+	while (si->inuse_pages &&
+	       !signal_pending(current) &&
+	       (i = find_next_to_unuse(si, i, frontswap)) != 0) {
 
 		entry = swp_entry(type, i);
 		page = find_get_page(swap_address_space(entry), i);
@@ -2123,8 +2123,11 @@ retry:
 	 * separate lists, and wait for those lists to be emptied; but it's
 	 * easier and more robust (though cpu-intensive) just to keep retrying.
 	 */
-	if (si->inuse_pages)
-		goto retry;
+	if (si->inuse_pages) {
+		if (!signal_pending(current))
+			goto retry;
+		retval = -EINTR;
+	}
 out:
 	return (retval == FRONTSWAP_PAGES_UNUSED) ? 0 : retval;
 }


  parent reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-08 19:53 [PATCH 0/4] mm: swapoff: fixes for 5.1-rc Hugh Dickins
2019-04-08 19:56 ` [PATCH 1/4] mm: swapoff: shmem_find_swap_entries() filter out other types Hugh Dickins
2019-04-08 19:58 ` [PATCH 2/4] mm: swapoff: remove too limiting SWAP_UNUSE_MAX_TRIES Hugh Dickins
2019-04-08 19:59 ` Hugh Dickins [this message]
2019-04-08 20:01 ` [PATCH 4/4] mm: swapoff: shmem_unuse() stop eviction without igrab() Hugh Dickins
2019-04-09  7:50   ` Konstantin Khlebnikov
2019-04-09 18:43     ` Hugh Dickins

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