From patchwork Tue Nov 3 09:27:19 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 11876711 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9D4D9697 for ; Tue, 3 Nov 2020 10:33:53 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4D72C22404 for ; Tue, 3 Nov 2020 10:33:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="iJ/nMPZ/"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="YkjV/BXf" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4D72C22404 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linutronix.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id DBF4E6B0080; Tue, 3 Nov 2020 05:33:36 -0500 (EST) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id D6EC26B0088; Tue, 3 Nov 2020 05:33:36 -0500 (EST) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B24DB6B0089; Tue, 3 Nov 2020 05:33:36 -0500 (EST) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0050.hostedemail.com [216.40.44.50]) by kanga.kvack.org (Postfix) with ESMTP id 6C97D6B0082 for ; Tue, 3 Nov 2020 05:33:36 -0500 (EST) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 0751D181AC9CC for ; Tue, 3 Nov 2020 10:33:36 +0000 (UTC) X-FDA: 77442745632.08.board00_370922c272b7 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin08.hostedemail.com (Postfix) with ESMTP id CA8B91819E766; Tue, 3 Nov 2020 10:33:35 +0000 (UTC) X-Spam-Summary: 1,0,0,af7d2cc36ea554df,d41d8cd98f00b204,tglx@linutronix.de,,RULES_HIT:41:152:355:379:800:960:988:989:1183:1260:1277:1311:1313:1314:1345:1437:1515:1516:1518:1535:1541:1593:1594:1711:1730:1747:1777:1792:1981:2194:2199:2393:2559:2562:3138:3139:3140:3141:3142:3353:3865:3867:3868:3870:3871:3874:4560:5007:6261:6653:6742:6743:10004:10400:11026:11232:11473:11658:11914:12043:12050:12160:12296:12297:12438:13069:13146:13230:13311:13357:14096:14097:14181:14659:14721:21080:21451:21627:21740:21966:30012:30054:30091,0,RBL:193.142.43.55:@linutronix.de:.lbl8.mailshell.net-62.2.6.100 64.100.201.201;04yg9aoptf8n38effmhg3jeujwm8hopp6787fzed3rah745w8gct4qdq8qbmyi7.3fscm371niz9wqq6hd8hez99476ricu857a7dkyga76r8cq8849gt1w4pdg6yqk.g-lbl8.mailshell.net-223.238.255.100,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime:67,LUA_SUMMARY:none X-HE-Tag: board00_370922c272b7 X-Filterd-Recvd-Size: 5812 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by imf46.hostedemail.com (Postfix) with ESMTP; Tue, 3 Nov 2020 10:33:34 +0000 (UTC) Message-Id: <20201103095857.268258322@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1604399611; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: references:references; bh=mZznvRq2pjMB0UxfV7Tofiw+ZX8bqdvzvy1elzwqCM0=; b=iJ/nMPZ/ADH458Z97fsOSw5wf904BzHADYKEdaFCBP8jKIH9j+SxmjzGepeQQmEuDdNCyA XxWrtJu+F6lu3Lp7uDpoRKHumZPJMpKU0JAHitmBCq936hqJimtruAT0Rlh/aJD2nJW2U2 sNv+WzdDOcpqWuWjf03Z6cFdbYts7znLi/vRFm9Inq1DOBuw4Cv5ZvCTAkemTzZPRqX9Us A/gXqaxzBtunufmgE+J6ou52fpkTr0wPHTsN2lG/n5pspmhs9CquSUQH5jaynAXffSMhb0 Y/avkAR9q97xAA+G8lllFeR3zkhF27Vtrd+kwqZDO8mrS5ZturOc+6Mxv/CPoQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1604399611; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: references:references; bh=mZznvRq2pjMB0UxfV7Tofiw+ZX8bqdvzvy1elzwqCM0=; b=YkjV/BXfl1xf/PJwkxxRp2il3aCsOfTo0zpayVu8o2qPQTr7lA/QrCtxb7deyA8IfhHH+y cIngF4mt/rXTgQCg== Date: Tue, 03 Nov 2020 10:27:19 +0100 From: Thomas Gleixner To: LKML Cc: Linus Torvalds , Peter Zijlstra , Paul McKenney , Christoph Hellwig , Sebastian Andrzej Siewior , Andrew Morton , linux-mm@kvack.org, Alexander Viro , Benjamin LaHaise , linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, Chris Mason , Josef Bacik , David Sterba , linux-btrfs@vger.kernel.org, x86@kernel.org, Vineet Gupta , linux-snps-arc@lists.infradead.org, Russell King , Arnd Bergmann , linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, Michal Simek , Thomas Bogendoerfer , linux-mips@vger.kernel.org, Nick Hu , Greentime Hu , Vincent Chen , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , linuxppc-dev@lists.ozlabs.org, "David S. Miller" , sparclinux@vger.kernel.org, Chris Zankel , Max Filippov , linux-xtensa@linux-xtensa.org, Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Christian Koenig , Huang Rui , David Airlie , Daniel Vetter , dri-devel@lists.freedesktop.org, VMware Graphics , Roland Scheidegger , Dave Airlie , Gerd Hoffmann , virtualization@lists.linux-foundation.org, spice-devel@lists.freedesktop.org, Ben Skeggs , nouveau@lists.freedesktop.org, Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , intel-gfx@lists.freedesktop.org Subject: [patch V3 07/37] highmem: Make DEBUG_HIGHMEM functional References: <20201103092712.714480842@linutronix.de> MIME-Version: 1.0 Content-transfer-encoding: 8-bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: For some obscure reason when CONFIG_DEBUG_HIGHMEM is enabled the stack depth is increased from 20 to 41. But the only thing DEBUG_HIGHMEM does is to enable a few BUG_ON()'s in the mapping code. That's a leftover from the historical mapping code which had fixed entries for various purposes. DEBUG_HIGHMEM inserted guard mappings between the map types. But that got all ditched when kmap_atomic() switched to a stack based map management. Though the WITH_KM_FENCE magic survived without being functional. All the thing does today is to increase the stack depth. Add a working implementation to the generic kmap_local* implementation. Signed-off-by: Thomas Gleixner --- V3: New patch --- mm/highmem.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) --- a/mm/highmem.c +++ b/mm/highmem.c @@ -374,9 +374,19 @@ EXPORT_SYMBOL(kunmap_high); static DEFINE_PER_CPU(int, __kmap_local_idx); +/* + * With DEBUG_HIGHMEM the stack depth is doubled and every second + * slot is unused which acts as a guard page + */ +#ifdef CONFIG_DEBUG_HIGHMEM +# define KM_INCR 2 +#else +# define KM_INCR 1 +#endif + static inline int kmap_local_idx_push(void) { - int idx = __this_cpu_inc_return(__kmap_local_idx) - 1; + int idx = __this_cpu_add_return(__kmap_local_idx, KM_INCR) - 1; WARN_ON_ONCE(in_irq() && !irqs_disabled()); BUG_ON(idx >= KM_MAX_IDX); @@ -390,7 +400,7 @@ static inline int kmap_local_idx(void) static inline void kmap_local_idx_pop(void) { - int idx = __this_cpu_dec_return(__kmap_local_idx); + int idx = __this_cpu_sub_return(__kmap_local_idx, KM_INCR); BUG_ON(idx < 0); }