Re: [PATCHv2 1/8] mm: Fix endless reclaim on machines with unaccepted memory

[Jianxiong Gao <jxgao@google.com>]

On Fri, Aug 9, 2024 at 4:49 AM Kirill A. Shutemov
<kirill.shutemov@linux.intel.com> wrote:
>
> Unaccepted memory is considered unusable free memory, which is not
> counted as free on the zone watermark check. This causes
> get_page_from_freelist() to accept more memory to hit the high
> watermark, but it creates problems in the reclaim path.
>
> The reclaim path encounters a failed zone watermark check and attempts
> to reclaim memory. This is usually successful, but if there is little or
> no reclaimable memory, it can result in endless reclaim with little to
> no progress. This can occur early in the boot process, just after start
> of the init process when the only reclaimable memory is the page cache
> of the init executable and its libraries.
>
> Make unaccepted memory free from watermark check point of view. This way
> unaccepted memory will never be the trigger of memory reclaim.
> Accept more memory in the get_page_from_freelist() if needed.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Reported-by: Jianxiong Gao <jxgao@google.com>
> Acked-by: David Hildenbrand <david@redhat.com>
> Fixes: dcdfdd40fa82 ("mm: Add support for unaccepted memory")
> Cc: stable@vger.kernel.org # v6.5+

Tested-by: Jianxiong Gao <jxgao@google.com>
I have verified that the patch fixes the systemd issue reported.