diff mbox

[dpdk-dev,v3,2/2] memalloc: keep in mind a failed MAP_FIXED mmap may still perform an unmap

Message ID 1527857960-109306-2-git-send-email-dariuszx.stojaczyk@intel.com (mailing list archive)
State Accepted, archived
Delegated to: Thomas Monjalon
Headers show

Checks

Context Check Description
ci/checkpatch success coding style OK
ci/Intel-compilation success Compilation OK

Commit Message

Stojaczyk, DariuszX June 1, 2018, 12:59 p.m. UTC
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.

Changes from v2:
 * added "git fixline" tags

Changes from v1:
 * checkpatch fixes
 * remapping is now done regardless of the mmap errno

Fixes: 582bed1e1d1d ("mem: support mapping hugepages at runtime")
Cc: anatoly.burakov@intel.com
Cc: stable@dpdk.org

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

Comments

Anatoly Burakov June 1, 2018, 3:07 p.m. UTC | #1
On 01-Jun-18 1:59 PM, Dariusz Stojaczyk wrote:
> 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.
> 
> Changes from v2:
>   * added "git fixline" tags
> 
> Changes from v1:
>   * checkpatch fixes
>   * remapping is now done regardless of the mmap errno
> 
> Fixes: 582bed1e1d1d ("mem: support mapping hugepages at runtime")
> Cc: anatoly.burakov@intel.com
> Cc: stable@dpdk.org
> 
> Signed-off-by: Dariusz Stojaczyk <dariuszx.stojaczyk@intel.com>
> ---

Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>

Version changes should not be part of commit message. Thomas, could you 
please fix this on apply?
diff mbox

Patch

diff --git a/lib/librte_eal/linuxapp/eal/eal_memalloc.c b/lib/librte_eal/linuxapp/eal/eal_memalloc.c
index 6be6680..81c94d5 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;