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Message-ID: <20230128072014.1030445-1-xialonglong1@huawei.com> Date: Sat, 28 Jan 2023 07:20:14 +0000 From: Longlong Xia <xialonglong1@...wei.com> To: <akpm@...ux-foundation.org> CC: <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>, <ying.huang@...el.com>, <chenwandun@...wei.com>, <wangkefeng.wang@...wei.com>, <sunnanyong@...wei.com>, Longlong Xia <xialonglong1@...wei.com> Subject: [RFC PATCH] mm/swapfile: add cond_resched() in get_swap_pages() We found that the plist_for_each_entry_safe() loop in get_swap_pages() could reach tens of thousands of times to find available space (extreme case: cond_resched() is not called in the loop). The test scenario is like commit de1ccfb64824 ("swapfile: fix soft lockup in scan_swap_map_slots") does. On the other hand, scan_swap_map_slots() needs to reach LATENCY_LIMIT before calling cond_resched(), so cond_resched() is needed when failed to find available space to avoid softlockup. Signed-off-by: Longlong Xia <xialonglong1@...wei.com> --- mm/swapfile.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/swapfile.c b/mm/swapfile.c index 908a529bca12..4fa440e87cd6 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1100,6 +1100,7 @@ int get_swap_pages(int n_goal, swp_entry_t swp_entries[], int entry_size) goto check_out; pr_debug("scan_swap_map of si %d failed to find offset\n", si->type); + cond_resched(); spin_lock(&swap_avail_lock); nextsi: -- 2.25.1
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