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

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

On 28-Feb-21 1:21 PM, Roy Shterman wrote:
> 
> 
> On Mon, Feb 22, 2021 at 5:53 PM Burakov, Anatoly 
> <anatoly.burakov@intel.com <mailto:anatoly.burakov@intel.com>> wrote:
> 
>     On 22-Feb-21 10:41 AM, Roy Shterman wrote:
>      > 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 <roy.shterman@vastdata.com
>     <mailto:roy.shterman@vastdata.com>>
> 
>     Cc: stable@dpdk.org <mailto: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?

Not automatically, generally you should add a CC to stable for the patch 
to be considered as part of stable release. That said, usually Fixed: 
tag is also used to determine whether a patch is backport-able, so 
having a correctly identified Fixed: tag is a mandatory minimum :)

> Also I wonder if you had more time to review this one?

Not yet, but i'll try to make some time this week.

> 
> 
>     -- 
>     Thanks,
>     Anatoly
> 
> 
> Thanks,
> Roy


-- 
Thanks,
Anatoly