From: Song Liu <songliubraving@fb.com>
To: <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
<akpm@linux-foundation.org>
Cc: <matthew.wilcox@oracle.com>, <kernel-team@fb.com>,
<william.kucharski@oracle.com>, <kirill.shutemov@linux.intel.com>,
Song Liu <songliubraving@fb.com>, Hugh Dickins <hughd@google.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Matthew Wilcox <willy@infradead.org>
Subject: [PATCH v5 2/2] mm/thp: flush file for !is_shmem PageDirty() case in collapse_file()
Date: Tue, 5 Nov 2019 22:09:30 -0800 [thread overview]
Message-ID: <20191106060930.2571389-3-songliubraving@fb.com> (raw)
In-Reply-To: <20191106060930.2571389-1-songliubraving@fb.com>
For non-shmem file THPs, khugepaged only collapses read only .text mapping
(VM_DENYWRITE). These pages should not be dirty except the case where the
file hasn't been flushed since first write.
Call filemap_flush() in collapse_file() to accelerate the write back in
such cases.
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Song Liu <songliubraving@fb.com>
---
[songliubraving@fb.com: flush file for !is_shmem PageDirty() case in collapse_file()]
https://lkml.kernel.org/linux-mm/20191030200736.3455046-1-songliubraving@fb.com/
---
mm/khugepaged.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 40215795d641..513cce897794 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1601,6 +1601,24 @@ static void collapse_file(struct mm_struct *mm,
result = SCAN_FAIL;
goto xa_unlocked;
}
+ } else if (PageDirty(page)) {
+ /*
+ * khugepaged only works on read-only fd,
+ * so this page is dirty because it hasn't
+ * been flushed since first write. There
+ * won't be new dirty pages.
+ *
+ * Trigger async flush here and hope the
+ * writeback is done when khugepaged
+ * revisits this page.
+ *
+ * This is a one-off situation. We are not
+ * forcing writeback in loop.
+ */
+ xas_unlock_irq(&xas);
+ filemap_flush(mapping);
+ result = SCAN_FAIL;
+ goto xa_unlocked;
} else if (trylock_page(page)) {
get_page(page);
xas_unlock_irq(&xas);
--
2.17.1
prev parent reply other threads:[~2019-11-06 6:12 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-06 6:09 [PATCH v5 0/2] fix and improvement for file THP Song Liu
2019-11-06 6:09 ` [PATCH v5 1/2] mm,thp: recheck each page before collapsing " Song Liu
2019-11-08 3:53 ` Andrew Morton
2019-11-08 3:58 ` Song Liu
2019-11-13 23:47 ` Song Liu
2019-11-15 0:10 ` Andrew Morton
2019-11-06 6:09 ` Song Liu [this message]
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