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Wed, 2 Sep 2026 21:06:08 +0800 (CST) Received: from kwepemk300003.china.huawei.com (unknown [7.202.195.93]) by mail.maildlp.com (Postfix) with ESMTPS id 9CB424057C; Wed, 2 Sep 2026 21:16:57 +0800 (CST) Received: from ubuntu (10.50.87.83) by kwepemk300003.china.huawei.com (7.202.195.93) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.45; Wed, 2 Sep 2026 21:16:56 +0800 From: Kefeng Wang To: , , , , , , , , , , , , , CC: , , , Kefeng Wang Subject: [PATCH 4/4] mm: replace PF_KCOMPACTD flag with kthread_func() check Date: Wed, 2 Sep 2026 21:16:53 +0800 Message-ID: <20260902131653.1338227-5-wangkefeng.wang@huawei.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260902131653.1338227-1-wangkefeng.wang@huawei.com> References: <20260902131653.1338227-1-wangkefeng.wang@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.50.87.83] X-ClientProxiedBy: kwepems500002.china.huawei.com (7.221.188.17) To kwepemk300003.china.huawei.com (7.202.195.93) X-Rspamd-Server: rspam11 X-Rspam-User: X-Stat-Signature: p1y6awksw6jps1wz73c1x74ray158iox X-Rspamd-Queue-Id: 083E618000C X-HE-Tag: 1788355021-282011 X-HE-Meta: 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 yAqn1wGe S/0JIAfyDwzEtI8TujgC/J4nrZmb2f5/aTb9fynTG9ron/hM8DBJSKRqOt51wCizHFkS7J2xSa5CoED/ktWZDP4JDYrzOaWtVvCQtQs4XnOIbRA2vS3jTZu7UIja+t13zVc4jablqukCxZ/3VcMNZCQHAzCYGxw2AeVwq075icAS0LfY3UzRWDlAGJ4t15FDZgvGthD8FT0HMmHTkT7EgumSbewf0vwRaIg3/9GRiI/XkOZfOPtvibG8G6BBV/bM6zSb4I+torRowoWZDqZp4LCXBHzrrqfWDsGaApahVlxm3U9tC/yE9XCxkDNyTBoAAdYqmcqdV4nkNoAKVRgFmu4DSlA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: PF_KCOMPACTD was introduced by commit ce6d9c1c2b5c ("NFS: fix nfs_release_folio() to not deadlock via kcompactd writeback") so nfs_release_folio() could detect kcompactd context and skip writeback. The flag is only consumed by current_is_kcompactd(), whose sole caller is nfs_release_folio(). Replace the flag-based check with kthread_func(current) == kcompactd, freeing the 0x00010000 PF flag bit. Signed-off-by: Kefeng Wang --- include/linux/compaction.h | 11 ++++++----- include/linux/sched.h | 2 +- mm/compaction.c | 9 ++++++--- tools/sched_ext/include/scx/common.bpf.h | 1 - 4 files changed, 13 insertions(+), 10 deletions(-) diff --git a/include/linux/compaction.h b/include/linux/compaction.h index 66a2f70e9e01..691c09f0a697 100644 --- a/include/linux/compaction.h +++ b/include/linux/compaction.h @@ -81,10 +81,6 @@ static inline unsigned long compact_gap(unsigned int order) return min(2UL << order, COMPACT_CLUSTER_MAX); } -static inline int current_is_kcompactd(void) -{ - return current->flags & PF_KCOMPACTD; -} #ifdef CONFIG_COMPACTION @@ -103,7 +99,7 @@ extern void compaction_defer_reset(struct zone *zone, int order, bool compaction_zonelist_suitable(struct alloc_context *ac, int order, int alloc_flags, gfp_t gfp_mask); - +bool current_is_kcompactd(void); extern void __meminit kcompactd_run(int nid); extern void __meminit kcompactd_stop(int nid); extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int highest_zoneidx); @@ -120,6 +116,11 @@ static inline bool compaction_suitable(struct zone *zone, int order, return false; } +static inline bool current_is_kcompactd(void) +{ + return false; +} + static inline void kcompactd_run(int nid) { } diff --git a/include/linux/sched.h b/include/linux/sched.h index 86394121b6c0..eb12ff4cea6c 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1808,7 +1808,7 @@ extern struct pid *cad_pid; #define PF_USED_MATH 0x00002000 /* If unset the fpu must be initialized before use */ #define PF_USER_WORKER 0x00004000 /* Kernel thread cloned from userspace thread */ #define PF_NOFREEZE 0x00008000 /* This thread should not be frozen */ -#define PF_KCOMPACTD 0x00010000 /* I am kcompactd */ +#define PF__HOLE__00010000 0x00010000 #define PF__HOLE__00020000 0x00020000 #define PF_MEMALLOC_NOFS 0x00040000 /* All allocations inherit GFP_NOFS. See memalloc_nfs_save() */ #define PF_MEMALLOC_NOIO 0x00080000 /* All allocations inherit GFP_NOIO. See memalloc_noio_save() */ diff --git a/mm/compaction.c b/mm/compaction.c index a049415512c6..4994e200bbec 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -3197,7 +3197,6 @@ static int kcompactd(void *p) long default_timeout = msecs_to_jiffies(HPAGE_FRAG_CHECK_INTERVAL_MSEC); long timeout = default_timeout; - current->flags |= PF_KCOMPACTD; set_freezable(); pgdat->kcompactd_max_order = 0; @@ -3254,11 +3253,15 @@ static int kcompactd(void *p) pgdat->proactive_compact_trigger = false; } - current->flags &= ~PF_KCOMPACTD; - return 0; } +bool current_is_kcompactd(void) +{ + return kthread_func(current) == kcompactd; +} +EXPORT_SYMBOL_GPL(current_is_kcompactd); + /* * This kcompactd start function will be called by init and node-hot-add. * On node-hot-add, kcompactd will moved to proper cpus if cpus are hot-added. diff --git a/tools/sched_ext/include/scx/common.bpf.h b/tools/sched_ext/include/scx/common.bpf.h index 3e095343ae84..807ef881ce2d 100644 --- a/tools/sched_ext/include/scx/common.bpf.h +++ b/tools/sched_ext/include/scx/common.bpf.h @@ -31,7 +31,6 @@ #define PF_IDLE 0x00000002 /* I am an IDLE thread */ #define PF_IO_WORKER 0x00000010 /* Task is an IO worker */ #define PF_WQ_WORKER 0x00000020 /* I'm a workqueue worker */ -#define PF_KCOMPACTD 0x00010000 /* I am kcompactd */ #define PF_KTHREAD 0x00200000 /* I am a kernel thread */ #define PF_EXITING 0x00000004 #define CLOCK_MONOTONIC 1 -- 2.55.0