Message ID | 20201103095857.268258322@linutronix.de |
---|---|
State | New |
Headers | show
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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 <tglx@linutronix.de> To: LKML <linux-kernel@vger.kernel.org> Subject: [patch V3 07/37] highmem: Make DEBUG_HIGHMEM functional References: <20201103092712.714480842@linutronix.de> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201103_053339_778539_0416DA0F X-CRM114-Status: GOOD ( 16.35 ) X-Spam-Score: -0.9 (/) X-Spam-Report: SpamAssassin version 3.4.4 on merlin.infradead.org summary: Content analysis details: (-0.9 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at https://www.dnswl.org/, low trust [2a0a:51c0:0:12e:550:0:0:1 listed in] [list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain X-BeenThere: linux-snps-arc@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on Synopsys ARC Processors <linux-snps-arc.lists.infradead.org> List-Unsubscribe: <http://lists.infradead.org/mailman/options/linux-snps-arc>, <mailto:linux-snps-arc-request@lists.infradead.org?subject=unsubscribe> List-Archive: <http://lists.infradead.org/pipermail/linux-snps-arc/> List-Post: <mailto:linux-snps-arc@lists.infradead.org> List-Help: <mailto:linux-snps-arc-request@lists.infradead.org?subject=help> List-Subscribe: <http://lists.infradead.org/mailman/listinfo/linux-snps-arc>, <mailto:linux-snps-arc-request@lists.infradead.org?subject=subscribe> Cc: Juri Lelli <juri.lelli@redhat.com>, linux-aio@kvack.org, Peter Zijlstra <peterz@infradead.org>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Sebastian Andrzej Siewior <bigeasy@linutronix.de>, Joonas Lahtinen <joonas.lahtinen@linux.intel.com>, dri-devel@lists.freedesktop.org, virtualization@lists.linux-foundation.org, Ben Segall <bsegall@google.com>, Chris Mason <clm@fb.com>, Huang Rui <ray.huang@amd.com>, Paul Mackerras <paulus@samba.org>, Gerd Hoffmann <kraxel@redhat.com>, Daniel Bristot de Oliveira <bristot@redhat.com>, sparclinux@vger.kernel.org, Vincent Chen <deanbo422@gmail.com>, Christoph Hellwig <hch@lst.de>, Vincent Guittot <vincent.guittot@linaro.org>, Paul McKenney <paulmck@kernel.org>, Max Filippov <jcmvbkbc@gmail.com>, Michael Ellerman <mpe@ellerman.id.au>, x86@kernel.org, Russell King <linux@armlinux.org.uk>, linux-csky@vger.kernel.org, Ingo Molnar <mingo@kernel.org>, David Airlie <airlied@linux.ie>, VMware Graphics <linux-graphics-maintainer@vmware.com>, Mel Gorman <mgorman@suse.de>, nouveau@lists.freedesktop.org, Dave Airlie <airlied@redhat.com>, linux-snps-arc@lists.infradead.org, Ben Skeggs <bskeggs@redhat.com>, linux-xtensa@linux-xtensa.org, Arnd Bergmann <arnd@arndb.de>, intel-gfx@lists.freedesktop.org, Roland Scheidegger <sroland@vmware.com>, Josef Bacik <josef@toxicpanda.com>, Steven Rostedt <rostedt@goodmis.org>, Linus Torvalds <torvalds@linuxfoundation.org>, Alexander Viro <viro@zeniv.linux.org.uk>, spice-devel@lists.freedesktop.org, David Sterba <dsterba@suse.com>, Rodrigo Vivi <rodrigo.vivi@intel.com>, Dietmar Eggemann <dietmar.eggemann@arm.com>, linux-arm-kernel@lists.infradead.org, Jani Nikula <jani.nikula@linux.intel.com>, Chris Zankel <chris@zankel.net>, Michal Simek <monstr@monstr.eu>, Thomas Bogendoerfer <tsbogend@alpha.franken.de>, Nick Hu <nickhu@andestech.com>, linux-mm@kvack.org, Vineet Gupta <vgupta@synopsys.com>, linux-mips@vger.kernel.org, Christian Koenig <christian.koenig@amd.com>, Benjamin LaHaise <bcrl@kvack.org>, Daniel Vetter <daniel@ffwll.ch>, linux-fsdevel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>, linuxppc-dev@lists.ozlabs.org, "David S. Miller" <davem@davemloft.net>, linux-btrfs@vger.kernel.org, Greentime Hu <green.hu@gmail.com> Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-snps-arc" <linux-snps-arc-bounces@lists.infradead.org> Errors-To: linux-snps-arc-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org |
Series |
mm/highmem: Preemptible variant of kmap_atomic & friends
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expand
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--- 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); }
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 <tglx@linutronix.de> --- V3: New patch --- mm/highmem.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)