[dpdk-dev] [PATCH] mem: fix free segment when using huge-unlink option
From: Roy Shterman <hidden>
Date: 2021-02-23 08:05:18
Subsystem:
library code, the rest · Maintainers:
Andrew Morton, Linus Torvalds
When using huge_unlink we unlink the segment right
after allocation. Although we unlink the file we keep
the fd in fd_list so file still exist just the path deleted.
When freeing the hugepage we need to close the fd and assign
it with (-1) in fd_list for the page to be released.
The current flow fails rte_malloc in the following flow when working
with --huge-unlink option:
1. alloc_seg() for segment A -
We allocate segment, unlink the path to the segment
and keep the file descriptor in fd_list.
2. free_seg() for segment A -
We clear the segment metadata and return - without closing fd
or assigning (-1) in fd list.
3. alloc_seg() for segment A again -
We find segment A as available, try to allocate it,
find the old fd in fd_list try to unlink it
as part of alloc_seg() but failed because path doesn't exist.
The impact of such error is falsly failing rte_malloc()
although we have hugepages available.
Fixes: d435aad37da7 ("mem: support --huge-unlink mode")
Signed-off-by: Roy Shterman <redacted>
---
lib/librte_eal/linux/eal_memalloc.c | 14 ++------------
1 file changed, 2 insertions(+), 12 deletions(-)
diff --git a/lib/librte_eal/linux/eal_memalloc.c b/lib/librte_eal/linux/eal_memalloc.c
index 6dc1b2bae..c590d6043 100644
--- a/lib/librte_eal/linux/eal_memalloc.c
+++ b/lib/librte_eal/linux/eal_memalloc.c@@ -709,7 +709,6 @@ free_seg(struct rte_memseg *ms, struct hugepage_info *hi, uint64_t map_offset; char path[PATH_MAX]; int fd, ret = 0; - bool exit_early; const struct internal_config *internal_conf = eal_get_internal_configuration();
@@ -725,17 +724,8 @@ free_seg(struct rte_memseg *ms, struct hugepage_info *hi, eal_mem_set_dump(ms->addr, ms->len, false); - exit_early = false; - /* if we're using anonymous hugepages, nothing to be done */ - if (internal_conf->in_memory && !memfd_create_supported) - exit_early = true; - - /* if we've already unlinked the page, nothing needs to be done */ - if (!internal_conf->in_memory && internal_conf->hugepage_unlink) - exit_early = true; - - if (exit_early) { + if (internal_conf->in_memory && !memfd_create_supported) { memset(ms, 0, sizeof(*ms)); return 0; }
@@ -761,7 +751,7 @@ free_seg(struct rte_memseg *ms, struct hugepage_info *hi, /* if we're able to take out a write lock, we're the last one * holding onto this page. */ - if (!internal_conf->in_memory) { + if (!internal_conf->in_memory && !internal_conf->hugepage_unlink) { ret = lock(fd, LOCK_EX); if (ret >= 0) { /* no one else is using this page */
--
2.24.1