Re: [dpdk-dev] [PATCH] mem: fix free segment when using huge-unlink option

On Mon, Feb 22, 2021 at 5:53 PM Burakov, Anatoly [off-list ref]
wrote:

On 22-Feb-21 10:41 AM, Roy Shterman wrote:

quoted

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>

Cc: stable@dpdk.org

Provisionally, patch looks fine, but i'll have to have a closer look.

Hi Anatoly,

Do I need to send this patch also to stable or it will happen automatically
if the patch will reach the next release candidate?
Also I wonder if you had more time to review this one?

--
Thanks,
Anatoly

Thanks,
Roy