On 6/2/23 16:47, Johannes Weiner wrote:
> On Mon, May 29, 2023 at 12:38:07PM -0400, Johannes Weiner wrote:
>> On Mon, May 29, 2023 at 03:03:52PM +0200, Vlastimil Babka wrote:
>> > I think you simplified this part too much, so now once it runs out of
>> > retries, it will return false, while previously it would increase the priority.
>
> Here is the delta fix. If this looks good to everybody, can you please
> fold this into the patch you have in tree? Thanks!
>
> ---
> From 4b9429f9ef04fcb7bb5ffae0db8ea113b26d097b Mon Sep 17 00:00:00 2001
> From: Johannes Weiner <hannes@xxxxxxxxxxx>
> Date: Fri, 2 Jun 2023 16:02:37 +0200
> Subject: [PATCH] mm: compaction: simplify should_compact_retry() fix
>
> Vlastimil points out an unintended change. Previously when hitting
> max_retries we'd bump the priority level and restart the loop. Now we
> bail out and fail instead. Restore the original behavior.
>
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
For the 2/5 +fix
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
> ---
> mm/page_alloc.c | 24 +++++++++++++-----------
> 1 file changed, 13 insertions(+), 11 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 72660e924b95..e7d7db36582b 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -3768,6 +3768,15 @@ should_compact_retry(struct alloc_context *ac, int order, int alloc_flags,
> if (fatal_signal_pending(current))
> return false;
>
> + /*
> + * Compaction was skipped due to a lack of free order-0
> + * migration targets. Continue if reclaim can help.
> + */
> + if (compact_result == COMPACT_SKIPPED) {
> + ret = compaction_zonelist_suitable(ac, order, alloc_flags);
> + goto out;
> + }
> +
> /*
> * Compaction managed to coalesce some page blocks, but the
> * allocation failed presumably due to a race. Retry some.
> @@ -3785,17 +3794,10 @@ should_compact_retry(struct alloc_context *ac, int order, int alloc_flags,
> if (order > PAGE_ALLOC_COSTLY_ORDER)
> max_retries /= 4;
>
> - ret = ++(*compaction_retries) <= max_retries;
> - goto out;
> - }
> -
> - /*
> - * Compaction was skipped due to a lack of free order-0
> - * migration targets. Continue if reclaim can help.
> - */
> - if (compact_result == COMPACT_SKIPPED) {
> - ret = compaction_zonelist_suitable(ac, order, alloc_flags);
> - goto out;
> + if (++(*compaction_retries) <= max_retries) {
> + ret = true;
> + goto out;
> + }
> }
>
> /*
