From 4ea3fa9dd2e9c58920d73b1b2cd6bcc6f14ae0e0 Mon Sep 17 00:00:00 2001 From: Yosry Ahmed Date: Sat, 13 Apr 2024 02:24:04 +0000 Subject: [PATCH] mm: zswap: always shrink in zswap_store() if zswap_pool_reached_full Patch series "zswap same-filled and limit checking cleanups", v3. Miscellaneous cleanups for limit checking and same-filled handling in the store path. This series was broken out of the "zswap: store zero-filled pages more efficiently" series [1]. It contains the cleanups and drops the main functional changes. [1]https://lore.kernel.org/lkml/20240325235018.2028408-1-yosryahmed@google.com/ This patch (of 4): The cleanup code in zswap_store() is not pretty, particularly the 'shrink' label at the bottom that ends up jumping between cleanup labels. Instead of having a dedicated label to shrink the pool, just use zswap_pool_reached_full directly to figure out if the pool needs shrinking. zswap_pool_reached_full should be true if and only if the pool needs shrinking. The only caveat is that the value of zswap_pool_reached_full may be changed by concurrent zswap_store() calls between checking the limit and testing zswap_pool_reached_full in the cleanup code. This is fine because: - If zswap_pool_reached_full was true during limit checking then became false during the cleanup code, then someone else already took care of shrinking the pool and there is no need to queue the worker. That would be a good change. - If zswap_pool_reached_full was false during limit checking then became true during the cleanup code, then someone else hit the limit meanwhile. In this case, both threads will try to queue the worker, but it never gets queued more than once anyway. Also, calling queue_work() multiple times when the limit is hit could already happen today, so this isn't a significant change in any way. Link: https://lkml.kernel.org/r/20240413022407.785696-1-yosryahmed@google.com Link: https://lkml.kernel.org/r/20240413022407.785696-2-yosryahmed@google.com Signed-off-by: Yosry Ahmed Reviewed-by: Nhat Pham Reviewed-by: Chengming Zhou Acked-by: Johannes Weiner Cc: "Maciej S. Szmigiero" Signed-off-by: Andrew Morton --- mm/zswap.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/mm/zswap.c b/mm/zswap.c index e6cf6282f5fd..d753ad9d4591 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -1436,12 +1436,12 @@ bool zswap_store(struct folio *folio) if (cur_pages >= max_pages) { zswap_pool_limit_hit++; zswap_pool_reached_full = true; - goto shrink; + goto reject; } if (zswap_pool_reached_full) { if (cur_pages > zswap_accept_thr_pages()) - goto shrink; + goto reject; else zswap_pool_reached_full = false; } @@ -1547,6 +1547,8 @@ freepage: zswap_entry_cache_free(entry); reject: obj_cgroup_put(objcg); + if (zswap_pool_reached_full) + queue_work(shrink_wq, &zswap_shrink_work); check_old: /* * If the zswap store fails or zswap is disabled, we must invalidate the @@ -1557,10 +1559,6 @@ check_old: if (entry) zswap_entry_free(entry); return false; - -shrink: - queue_work(shrink_wq, &zswap_shrink_work); - goto reject; } bool zswap_load(struct folio *folio)