[dpdk-dev] [PATCH] mem: close rtemap files

[Stephen Hemminger]

The memory subsystem is leaving open a file descriptor for each
rtemap file. This can lead to hundreds of extra open file descriptors
which has negative side effects. For example, the application may go
over its maximum file descriptor limit, or the application may be using
limited API's like select that only allow 1024 file descriptors.

The EAL memory subsystem does not need to hold the file open.
Probably the original intention was to keep the file locked, but that is
not necessary. The Linux kernel keeps a reference count on the file,
and the mmap counts is a reference and therefore maintains the file
as locked.

The fix is one line just close the file after it is setup.

Fixes: 582bed1e1d1d ("mem: support mapping hugepages at runtime")
Cc: anatoly.burakov at intel.com
Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>
---
 lib/librte_eal/linux/eal_memalloc.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lib/librte_eal/linux/eal_memalloc.c b/lib/librte_eal/linux/eal_memalloc.c
index 6dc1b2baecdc..99600adda568 100644
--- a/lib/librte_eal/linux/eal_memalloc.c
+++ b/lib/librte_eal/linux/eal_memalloc.c
@@ -651,6 +651,12 @@ alloc_seg(struct rte_memseg *ms, void *addr, int socket_id,
 				__func__);
 #endif
 
+	/*
+	 * reference count is held by mmap() now
+	 * don't need to hold file open to keep it locked
+	 */
+	close(fd);
+
 	ms->addr = addr;
 	ms->hugepage_sz = alloc_sz;
 	ms->len = alloc_sz;
-- 
2.27.0