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From: Josef Bacik <josef@toxicpanda.com>
To: kernel-team@fb.com, linux-kernel@vger.kernel.org,
	hannes@cmpxchg.org, tj@kernel.org, linux-fsdevel@vger.kernel.org,
	akpm@linux-foundation.org, riel@redhat.com, linux-mm@kvack.org,
	linux-btrfs@vger.kernel.org
Cc: Johannes Weiner <jweiner@fb.com>
Subject: [PATCH 4/9] mm: drop mmap_sem for swap read IO submission
Date: Wed, 26 Sep 2018 17:08:51 -0400	[thread overview]
Message-ID: <20180926210856.7895-5-josef@toxicpanda.com> (raw)
In-Reply-To: <20180926210856.7895-1-josef@toxicpanda.com>

From: Johannes Weiner <jweiner@fb.com>

We don't need to hold the mmap_sem while we're doing the IO, simply drop
it and retry appropriately.

Signed-off-by: Johannes Weiner <jweiner@fb.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
 mm/page_io.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/mm/page_io.c b/mm/page_io.c
index aafd19ec1db4..bf21b56a964e 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -365,6 +365,20 @@ int swap_readpage(struct page *page, bool synchronous)
 		goto out;
 	}
 
+	/*
+	 * XXX:
+	 *
+	 * Propagate mm->mmap_sem into this function. Then:
+	 *
+	 * get_file(sis->swap_file)
+	 * up_read(mm->mmap_sem)
+	 * submit io request
+	 * fput
+	 *
+	 * After mmap_sem is dropped, sis is no longer valid. Go
+	 * through swap_file->blah->bdev.
+	 */
+
 	if (sis->flags & SWP_FILE) {
 		struct file *swap_file = sis->swap_file;
 		struct address_space *mapping = swap_file->f_mapping;
-- 
2.14.3

  parent reply	other threads:[~2018-09-26 21:08 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-26 21:08 [RFC][PATCH 0/9][V2] drop the mmap_sem when doing IO in the fault path Josef Bacik
2018-09-26 21:08 ` [PATCH 1/9] mm: infrastructure for page fault page caching Josef Bacik
2018-09-27 16:24   ` Matthew Wilcox
2018-09-26 21:08 ` [PATCH 2/9] mm: drop mmap_sem for page cache read IO submission Josef Bacik
2018-09-26 21:08 ` [PATCH 3/9] mm: clean up swapcache lookup and creation function names Josef Bacik
2018-09-26 21:08 ` Josef Bacik [this message]
2018-09-26 21:08 ` [PATCH 5/9] mm: drop the mmap_sem in all read fault cases Josef Bacik
2018-09-26 21:08 ` [PATCH 6/9] mm: use the cached page for filemap_fault Josef Bacik
2018-09-26 21:08 ` [PATCH 7/9] mm: add a flag to indicate we used a cached page Josef Bacik
2018-09-26 21:08 ` [PATCH 8/9] mm: allow ->page_mkwrite to do retries Josef Bacik
2018-09-26 21:08 ` [PATCH 9/9] btrfs: drop mmap_sem in mkwrite for btrfs Josef Bacik

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