From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-165.mta1.migadu.com [95.215.58.165]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 079AD44F561 for ; Fri, 9 Oct 2026 06:36:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.165 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791527791; cv=none; b=YCMkD8RJlKOaifDPvmOOFR/JCHlBwOh2G/mGFj22Tf+djeot5p7wzllwTfG+5aXiuW3BMQXtunLotGaYcWPx1kTjpeuqFEZ753siwvy3ZCwOgp1DsqA+6C1t8A4lfMKMKoh9iiOiLCEzuZJNRMqkHVPKBxB3+KC6LeZFYLDniHA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791527791; c=relaxed/simple; bh=XX490udm4Ta6ALheN6Xuua3sT0ZXTpdEDmRJNuiAJBs=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=eg7ajLDIulNGY+5U7Gr5D+L/PHCpRKjjuKptkdOEUCFpjG68DiuJAZyYympBgD5PuIdEVQftLOxMlqj+nsRADvmth1GybkTTPoYf98whG6yCeIkEiBWz1ZHpRbXUAKYPaQJIADTt87mRU0hA3yiadodGid8vph5T24QBxOmihmw= 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=Tq5jaOpF; arc=none smtp.client-ip=95.215.58.165 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="Tq5jaOpF" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=XX490udm4Ta6ALheN6Xuua3sT0ZXTpdEDmRJNuiAJBs=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1791527782; v=1; x=1792132582; b=Tq5jaOpF3DaN/KjM1sTJ9Kt+qtUR74OOFPzsUK5mu/rJy7iP8nwLZ/U5qbYT1NJrDtUpI0m4 Pr3i264mbDoSlhbZEgkdKDC4I4tpufbBOvXapzekMxm/smgT4vG8u5GvDFPRUlx8gN8+xMFt9tz I0h43YIcNzUzCi+1GNSf+5t4= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id a2f462b3a15301f0; Fri, 09 Oct 2026 06:36:22 +0000 X-Mizu-Trace-ID: a2f462b3a15301f0 X-Migadu-Flow: FLOW_OUT From: Hao Ge To: Suren Baghdasaryan , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , "Christophe Leroy (CS GROUP)" , "Ritesh Harjani (IBM)" , Shrikanth Hegde , Alexander Potapenko , Marco Elver , Dmitry Vyukov , Andrew Morton , Dennis Zhou , Tejun Heo , Christoph Lameter , Uladzislau Rezki Cc: Hao Ge , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org Subject: [RFC PATCH 4/4] mm/percpu: stop unmapping the CPU that failed to map Date: Fri, 9 Oct 2026 14:36:19 +0800 Message-Id: <20261009063619.112313-5-hao.ge@linux.dev> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20261009063619.112313-1-hao.ge@linux.dev> References: <20261009063619.112313-1-hao.ge@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 __pcpu_map_pages() clears the PTEs it installed when it fails, so pcpu_map_pages() only has to tear down the CPUs it mapped before the failing one. Signed-off-by: Hao Ge --- mm/percpu-vm.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/mm/percpu-vm.c b/mm/percpu-vm.c index 509d8901835c..59d3a336a6bd 100644 --- a/mm/percpu-vm.c +++ b/mm/percpu-vm.c @@ -252,10 +252,11 @@ static int pcpu_map_pages(struct pcpu_chunk *chunk, struct page **pages, return 0; err: for_each_possible_cpu(tcpu) { - __pcpu_unmap_pages(pcpu_chunk_addr(chunk, tcpu, page_start), - page_end - page_start); + /* The failing CPU's partial mapping undoes itself */ if (tcpu == cpu) break; + __pcpu_unmap_pages(pcpu_chunk_addr(chunk, tcpu, page_start), + page_end - page_start); } pcpu_post_unmap_tlb_flush(chunk, page_start, page_end); return err; -- 2.25.1