[dpdk-stable] patch 'mem: do not unmap overlapping region on mmap failure' has been queued to stable release 18.05.1

[Christian Ehrhardt]

Hi,

FYI, your patch has been queued to stable release 18.05.1

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 08/01/18. So please
shout if anyone has objections.

Thanks.

Christian Ehrhardt <christian.ehrhardt at canonical.com>

---
>From ca9746df21edfc99ef63bce5f24c8762d5a98add Mon Sep 17 00:00:00 2001
From: Dariusz Stojaczyk <dariuszx.stojaczyk at intel.com>
Date: Fri, 1 Jun 2018 14:59:20 +0200
Subject: [PATCH] mem: do not unmap overlapping region on mmap failure

[ upstream commit 0762c438b8da8486b283f4da0c01a85f684b8896 ]

This isn't documented in the manuals, but a failed
mmap(..., MAP_FIXED) may still unmap overlapping
regions. In such case, we need to remap these regions
back into our address space to ensure mem contiguity.
We do it unconditionally now on mmap failure just to
be safe.

Verified on Linux 4.9.0-4-amd64. I was getting
ENOMEM when trying to map hugetlbfs with no space
left, and the previous anonymous mapping was still
being removed.

Fixes: 582bed1e1d1d ("mem: support mapping hugepages at runtime")

Signed-off-by: Dariusz Stojaczyk <dariuszx.stojaczyk at intel.com>
Acked-by: Anatoly Burakov <anatoly.burakov at intel.com>
---
 lib/librte_eal/linuxapp/eal/eal_memalloc.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/librte_eal/linuxapp/eal/eal_memalloc.c b/lib/librte_eal/linuxapp/eal/eal_memalloc.c
index 6be668055..81c94d54e 100644
--- a/lib/librte_eal/linuxapp/eal/eal_memalloc.c
+++ b/lib/librte_eal/linuxapp/eal/eal_memalloc.c
@@ -527,7 +527,10 @@ alloc_seg(struct rte_memseg *ms, void *addr, int socket_id,
 	if (va == MAP_FAILED) {
 		RTE_LOG(DEBUG, EAL, "%s(): mmap() failed: %s\n", __func__,
 			strerror(errno));
-		goto resized;
+		/* mmap failed, but the previous region might have been
+		 * unmapped anyway. try to remap it
+		 */
+		goto unmapped;
 	}
 	if (va != addr) {
 		RTE_LOG(DEBUG, EAL, "%s(): wrong mmap() address\n", __func__);
@@ -588,6 +591,7 @@ alloc_seg(struct rte_memseg *ms, void *addr, int socket_id,
 
 mapped:
 	munmap(addr, alloc_sz);
+unmapped:
 	flags = MAP_FIXED;
 #ifdef RTE_ARCH_PPC_64
 	flags |= MAP_HUGETLB;
-- 
2.17.1