From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 07F901F4708; Wed, 6 Nov 2024 12:54:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730897644; cv=none; b=T3XxhIf2Pu6AQCR23DibZ5T9rZh6d7SS0BRrV5U77mOAwyV/gxHbMB1CqXp0q8PJ+qK9Uxx3Qy2hCg7KRKRXE9EoH0hLRqdtvaek2+jpmzDbiQrJ45WcsRfnS9vQYTQj6GOaOSynQNy+ZOn0Jwh6TaMqVFJ1GyryDpUfgekDuqA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730897644; c=relaxed/simple; bh=qbFPHYFPAK14Rj8LuFImtwjZmXKiX6ModhTIKpDZ0OA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=szbvYzq/qf3R+id/xLaViNSIYqiBSQ2fawSktu6gblWT4gvEO4+mQUsN2UZZMzg0YnClJvZ//OOI66kfb9V84/iMrvU56E4luuucLEDbTWYlDW2SIG3PaVYQznXREDT+zY88NOhbdQwC+b/N4nqulhXAg0tO3gwjQc+zuC7dd4g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=HCXfMQTA; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="HCXfMQTA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 39EA5C4CECD; Wed, 6 Nov 2024 12:54:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1730897643; bh=qbFPHYFPAK14Rj8LuFImtwjZmXKiX6ModhTIKpDZ0OA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HCXfMQTAArEj/YIeuGwbxN17/DJOQiMo9oTSzWhr/KLxAi6xcktjf+xnquugO9v5j Tsdhl3zhdB72hcdEXPk3Ifq05ffQZRU4/TNt9arBmjQ0s9MeAcpceB1SsRPfL6E2DH ALzegXqMtDnfa7K4zUAbBWIE5baI7aMxxt8DYeZQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Hugh Dickins , Christoph Hellwig , Christian Brauner , Sasha Levin Subject: [PATCH 6.6 123/151] iov_iter: fix copy_page_from_iter_atomic() if KMAP_LOCAL_FORCE_MAP Date: Wed, 6 Nov 2024 13:05:11 +0100 Message-ID: <20241106120312.250634648@linuxfoundation.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241106120308.841299741@linuxfoundation.org> References: <20241106120308.841299741@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Hugh Dickins [ Upstream commit c749d9b7ebbc5716af7a95f7768634b30d9446ec ] generic/077 on x86_32 CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP=y with highmem, on huge=always tmpfs, issues a warning and then hangs (interruptibly): WARNING: CPU: 5 PID: 3517 at mm/highmem.c:622 kunmap_local_indexed+0x62/0xc9 CPU: 5 UID: 0 PID: 3517 Comm: cp Not tainted 6.12.0-rc4 #2 ... copy_page_from_iter_atomic+0xa6/0x5ec generic_perform_write+0xf6/0x1b4 shmem_file_write_iter+0x54/0x67 Fix copy_page_from_iter_atomic() by limiting it in that case (include/linux/skbuff.h skb_frag_must_loop() does similar). But going forward, perhaps CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP is too surprising, has outlived its usefulness, and should just be removed? Fixes: 908a1ad89466 ("iov_iter: Handle compound highmem pages in copy_page_from_iter_atomic()") Signed-off-by: Hugh Dickins Link: https://lore.kernel.org/r/dd5f0c89-186e-18e1-4f43-19a60f5a9774@google.com Reviewed-by: Christoph Hellwig Cc: stable@vger.kernel.org Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin --- lib/iov_iter.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 27234a820eeb3..a4bb47efafe37 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -570,6 +570,8 @@ size_t copy_page_from_iter_atomic(struct page *page, size_t offset, size_t bytes, struct iov_iter *i) { size_t n, copied = 0; + bool uses_kmap = IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP) || + PageHighMem(page); if (!page_copy_sane(page, offset, bytes)) return 0; @@ -580,7 +582,7 @@ size_t copy_page_from_iter_atomic(struct page *page, size_t offset, char *p; n = bytes - copied; - if (PageHighMem(page)) { + if (uses_kmap) { page += offset / PAGE_SIZE; offset %= PAGE_SIZE; n = min_t(size_t, n, PAGE_SIZE - offset); @@ -594,7 +596,7 @@ size_t copy_page_from_iter_atomic(struct page *page, size_t offset, kunmap_atomic(p); copied += n; offset += n; - } while (PageHighMem(page) && copied != bytes && n > 0); + } while (uses_kmap && copied != bytes && n > 0); return copied; } -- 2.43.0