From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-188.mta0.migadu.com (out-188.mta0.migadu.com [91.218.175.188]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 39E6C352015 for ; Fri, 26 Jun 2026 02:46:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782441972; cv=none; b=dXMLMK3EbCbUfFW/YQw0r1j8CXN7IyY6ytO3YdCZSFdZqWhN5zYCjKaibfMkH5gqQXRfHy/ZC6Xz+G1g0g/xJuV98LWJw93Q0tFJkt5H1Wprr5I6B/Xiye89s5oCwRPBTbxgbTTdYtK2KeAw87udGl/cCyebL13Xq3L5lVY90iA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782441972; c=relaxed/simple; bh=vgvo7vOy3aKMOSqxd6VhxRAiYxpECE3FF4Ynhb37Rkc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Q7Asl0qCws4gmIY7xluHvMxsluWmkuzHGl9DGNOZkAtRp08CvN+A/QwpzhlnmyxZMkuIZECFHBS7AKHbe/ZRT9pevMO465tf+4gZU27Ia1MYmmwsvWjPq6sWF//9mQrHkCBDgoDrVcmuKnNns/g2mA40VxlkXpfPcwzvZZNKlpo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=MuNcYjPT; arc=none smtp.client-ip=91.218.175.188 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="MuNcYjPT" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1782441969; 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=MuNcYjPTB0GgnR9RtSNJrEf2vkrdCPnkRQcySpNJ/NWqNCOdi4qwh0Fm04fcx7tDpdGN7J lvSCzFstf9W0WUx/4VNp4L8WrcXXf4ZGDQBaoyNryyQyqjLQJtBh3Fx15T0HccwW/PYDmu PlOSaHpdxnX2HHWR4b0PrXzZqSgNPE0= 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 v2 2/6] mm/page_owner: use MIGRATE_REASON_NONE instead of -1 for last_migrate_reason Date: Fri, 26 Jun 2026 10:45:41 +0800 Message-ID: <20260626024550.25677-3-ye.liu@linux.dev> In-Reply-To: <20260626024550.25677-1-ye.liu@linux.dev> References: <20260626024550.25677-1-ye.liu@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT 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