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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1782197572; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0dUyOBnUAmeOV/VpmEyx25JanzSfW2aamrhE6D4NgAk=; b=G+ifmTq0PVVelMYucTQ6pV5/6muw3la89CPy5zYvWWEh8aTHUPxICkMSXNwvapfFj66ZK7 Kz1U0h00Iu+ylmDVXYBnoSB71Wn68XpIJ3bz4Unbf8Gk/SzIiw6lINtipGTFCAHYKvkyEC xCsiIq5D1u3sjEbCQSRFb1CZ84bR61o= From: Ye Liu To: Andrew Morton , Vlastimil Babka Cc: Ye Liu , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/6] mm/page_owner: use MIGRATE_REASON_NONE instead of -1 for last_migrate_reason Date: Tue, 23 Jun 2026 14:52:27 +0800 Message-ID: <20260623065234.31866-3-ye.liu@linux.dev> In-Reply-To: <20260623065234.31866-1-ye.liu@linux.dev> References: <20260623065234.31866-1-ye.liu@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: C28744000B X-Stat-Signature: 8hpix33kpap3yddbxtdprdamigxrz4pn X-HE-Tag: 1782197573-135195 X-HE-Meta: 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 ViNNCfei W2kXL/wzSHUjygnosP7hG/O00vf8oUtre3cTJVUGmkLOBGx0d9yPkByWfYKZRCkMfw9sZl9ySF/qh+3mxruIklUkLIpPrQFEThAIi/tJYgcl7tAYdw2xXHHUFPLKW/M3a5oNKy9tmsmJQ+8otJcOgFeEex8yrAYy2MejDjg2BrzbTexN5pMg4ybPAWmAzx58p56KI0G/c/w9Nlm9xJJOWBsNZht5R9YA95XMm7U/N6OZv+imKOnuvO6wcSQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: The last_migrate_reason field uses -1 as a sentinel value to mean "no migration has happened". Replace the four bare -1 occurrences with a local MIGRATE_REASON_NONE define so the intent is explicit and the magic number is eliminated. No functional change. Signed-off-by: Ye Liu --- mm/page_owner.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/mm/page_owner.c b/mm/page_owner.c index 342549891a8d..ebafa9d7ff07 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -21,6 +21,13 @@ */ #define PAGE_OWNER_STACK_DEPTH (16) +/* + * Used to indicate that a page has never been migrated, as the valid + * migrate_reason values are non-negative enum members (MR_* in + * include/linux/migrate_mode.h). + */ +#define MIGRATE_REASON_NONE (-1) + struct page_owner { unsigned short order; short last_migrate_reason; @@ -339,7 +346,7 @@ noinline void __set_page_owner(struct page *page, unsigned short order, depot_stack_handle_t handle; handle = save_stack(gfp_mask); - __update_page_owner_handle(page, handle, order, gfp_mask, -1, + __update_page_owner_handle(page, handle, order, gfp_mask, MIGRATE_REASON_NONE, ts_nsec, current->pid, current->tgid, current->comm); inc_stack_record_count(handle, gfp_mask, 1 << order); @@ -596,7 +603,7 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn, if (ret >= count) goto err; - if (page_owner->last_migrate_reason != -1) { + if (page_owner->last_migrate_reason != MIGRATE_REASON_NONE) { ret += scnprintf(kbuf + ret, count - ret, "Page has been migrated, last migrate reason: %s\n", migrate_reason_names[page_owner->last_migrate_reason]); @@ -667,7 +674,7 @@ void __dump_page_owner(const struct page *page) stack_depot_print(handle); } - if (page_owner->last_migrate_reason != -1) + if (page_owner->last_migrate_reason != MIGRATE_REASON_NONE) pr_alert("page has been migrated, last migrate reason: %s\n", migrate_reason_names[page_owner->last_migrate_reason]); page_ext_put(page_ext); @@ -826,7 +833,7 @@ static void init_pages_in_zone(struct zone *zone) /* Found early allocated page */ __update_page_owner_handle(page, early_handle, 0, 0, - -1, local_clock(), current->pid, + MIGRATE_REASON_NONE, local_clock(), current->pid, current->tgid, current->comm); count++; ext_put_continue: -- 2.43.0