[dpdk-dev] [PATCH] mem: skip memory locking on failure

[Olivier Matz <olivier.matz@6wind.com>]

Since recently [1], it is not possible to run the dpdk with user
(non-root) privileges and the --no-huge option. This is because the eal
layer tries to lock the memory. Using locked memory is mandatory for
physical devices because they reference physical addresses.

But a user may want to start the dpdk without locked memory, because he
does not have the permission to do so, and/or does not have this need.

Moreover, the option --no-huge is still not functional today since the
physical memory address is not properly filled, so the initial patch is
not really useful.

This commit fixes this issue by retrying the mmap() wihout the
MAP_LOCKED flag if the first mmap() failed.

[1] http://www.dpdk.org/ml/archives/dev/2016-May/039404.html

Fixes: 593a084afc2b ("mem: lock pages when not using hugepages")
Reported-by: Panu Matilainen <pmatilai@redhat.com>
Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
---
 lib/librte_eal/linuxapp/eal/eal_memory.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/lib/librte_eal/linuxapp/eal/eal_memory.c b/lib/librte_eal/linuxapp/eal/eal_memory.c
index 79d1d2d..08692d1 100644
--- a/lib/librte_eal/linuxapp/eal/eal_memory.c
+++ b/lib/librte_eal/linuxapp/eal/eal_memory.c
@@ -1075,6 +1075,15 @@ rte_eal_hugepage_init(void)
 	if (internal_config.no_hugetlbfs) {
 		addr = mmap(NULL, internal_config.memory, PROT_READ | PROT_WRITE,
 			MAP_LOCKED | MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
+		/* retry without MAP_LOCKED */
+		if (addr == MAP_FAILED && errno == EAGAIN) {
+			addr = mmap(NULL, internal_config.memory,
+				PROT_READ | PROT_WRITE,
+				MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
+			if (addr != MAP_FAILED)
+				RTE_LOG(NOTICE, EAL,
+					"Cannot lock memory: don't use physical devices\n");
+		}
 		if (addr == MAP_FAILED) {
 			RTE_LOG(ERR, EAL, "%s: mmap() failed: %s\n", __func__,
 					strerror(errno));
-- 
2.8.0.rc3