From: Oleg Nesterov <oleg@redhat.com>
To: Al Viro <viro@ZenIV.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Benjamin LaHaise <bcrl@kvack.org>, Jeff Moyer <jmoyer@redhat.com>
Cc: linux-aio@kvack.org, linux-kernel@vger.kernel.org
Subject: [PATCH v3 3/3] aio_free_ring: don't do page_count(NULL)
Date: Thu, 18 Jun 2015 19:52:12 +0200 [thread overview]
Message-ID: <20150618175212.GA10067@redhat.com> (raw)
In-Reply-To: <20150618175143.GA10033@redhat.com>
aio_free_ring() can actually see the NULL page in ->ring_pages[],
this can happen if aio_setup_ring() fails.
And in this case page_count(ctx->ring_pages[i]) can OOPS.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
---
fs/aio.c | 8 ++++----
1 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/fs/aio.c b/fs/aio.c
index d63a889..b9947ed 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -292,12 +292,12 @@ static void aio_free_ring(struct kioctx *ctx)
put_aio_ring_file(ctx);
for (i = 0; i < ctx->nr_pages; i++) {
- struct page *page;
- pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i,
- page_count(ctx->ring_pages[i]));
- page = ctx->ring_pages[i];
+ struct page *page = ctx->ring_pages[i];
if (!page)
continue;
+
+ pr_debug("pid(%d) [%d] page->count=%d\n",
+ current->pid, i, page_count(page));
ctx->ring_pages[i] = NULL;
put_page(page);
}
--
1.5.5.1
prev parent reply other threads:[~2015-06-18 17:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-18 17:51 [PATCH v3 0/3] aio: ctx->dead cleanups Oleg Nesterov
2015-06-18 17:52 ` [PATCH v3 1/3] aio_ring_remap: kill the bogus ctx->dead check Oleg Nesterov
2015-06-18 17:52 ` [PATCH v3 2/3] aio: make aio_ring->dead boolean Oleg Nesterov
2015-06-18 18:02 ` Jeff Moyer
2015-06-18 18:27 ` Oleg Nesterov
2015-06-18 17:52 ` Oleg Nesterov [this message]
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