[3.11.y.z extended stable] Patch "IB/ipath: Convert ipath_user_sdma_pin_pages() to use" has been added to staging queue
Luis Henriques
luis.henriques at canonical.com
Thu Dec 5 11:22:54 UTC 2013
This is a note to let you know that I have just added a patch titled
IB/ipath: Convert ipath_user_sdma_pin_pages() to use
to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree
which can be found at:
http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Luis
------
>From 3eb9766ec5480083a117ee6b19b207dca01f224e Mon Sep 17 00:00:00 2001
From: Jan Kara <jack at suse.cz>
Date: Fri, 4 Oct 2013 09:29:06 -0400
Subject: IB/ipath: Convert ipath_user_sdma_pin_pages() to use
get_user_pages_fast()
commit 4adcf7fb6783e354aab38824d803fa8c4f8e8a27 upstream.
ipath_user_sdma_queue_pkts() gets called with mmap_sem held for
writing. Except for get_user_pages() deep down in
ipath_user_sdma_pin_pages() we don't seem to need mmap_sem at all.
Even more interestingly the function ipath_user_sdma_queue_pkts() (and
also ipath_user_sdma_coalesce() called somewhat later) call
copy_from_user() which can hit a page fault and we deadlock on trying
to get mmap_sem when handling that fault. So just make
ipath_user_sdma_pin_pages() use get_user_pages_fast() and leave
mmap_sem locking for mm.
This deadlock has actually been observed in the wild when the node
is under memory pressure.
Signed-off-by: Jan Kara <jack at suse.cz>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn at intel.com>
[ Merged in fix for call to get_user_pages_fast from Tetsuo Handa
<penguin-kernel at I-love.SAKURA.ne.jp>. - Roland ]
Signed-off-by: Roland Dreier <roland at purestorage.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
drivers/infiniband/hw/ipath/ipath_user_sdma.c | 7 +------
1 file changed, 1 insertion(+), 6 deletions(-)
diff --git a/drivers/infiniband/hw/ipath/ipath_user_sdma.c b/drivers/infiniband/hw/ipath/ipath_user_sdma.c
index f5cb13b..cc04b7b 100644
--- a/drivers/infiniband/hw/ipath/ipath_user_sdma.c
+++ b/drivers/infiniband/hw/ipath/ipath_user_sdma.c
@@ -280,9 +280,7 @@ static int ipath_user_sdma_pin_pages(const struct ipath_devdata *dd,
int j;
int ret;
- ret = get_user_pages(current, current->mm, addr,
- npages, 0, 1, pages, NULL);
-
+ ret = get_user_pages_fast(addr, npages, 0, pages);
if (ret != npages) {
int i;
@@ -811,10 +809,7 @@ int ipath_user_sdma_writev(struct ipath_devdata *dd,
while (dim) {
const int mxp = 8;
- down_write(¤t->mm->mmap_sem);
ret = ipath_user_sdma_queue_pkts(dd, pq, &list, iov, dim, mxp);
- up_write(¤t->mm->mmap_sem);
-
if (ret <= 0)
goto done_unlock;
else {
--
1.8.3.2
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