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[142.167.216.168]) by smtp.gmail.com with ESMTPSA id n21sm267524qtc.70.2019.08.27.15.50.03 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 27 Aug 2019 15:50:03 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1i2kHq-0002zw-Kb; Tue, 27 Aug 2019 19:50:02 -0300 Date: Tue, 27 Aug 2019 19:50:02 -0300 From: Jason Gunthorpe To: Daniel Vetter Cc: LKML , Linux MM , DRI Development , Peter Zijlstra , Ingo Molnar , Andrew Morton , Michal Hocko , David Rientjes , Christian =?utf-8?B?S8O2bmln?= , =?utf-8?B?SsOpcsO0bWU=?= Glisse , Masahiro Yamada , Wei Wang , Andy Shevchenko , Thomas Gleixner , Jann Horn , Feng Tang , Kees Cook , Randy Dunlap , Daniel Vetter Subject: Re: [PATCH 3/5] kernel.h: Add non_block_start/end() Message-ID: <20190827225002.GB30700@ziepe.ca> References: <20190826201425.17547-1-daniel.vetter@ffwll.ch> <20190826201425.17547-4-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190826201425.17547-4-daniel.vetter@ffwll.ch> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > diff --git a/include/linux/kernel.h b/include/linux/kernel.h > index 4fa360a13c1e..82f84cfe372f 100644 > +++ b/include/linux/kernel.h > @@ -217,7 +217,9 @@ extern void __cant_sleep(const char *file, int line, int preempt_offset); > * might_sleep - annotation for functions that can sleep > * > * this macro will print a stack trace if it is executed in an atomic > - * context (spinlock, irq-handler, ...). > + * context (spinlock, irq-handler, ...). Additional sections where blocking is > + * not allowed can be annotated with non_block_start() and non_block_end() > + * pairs. > * > * This is a useful debugging help to be able to catch problems early and not > * be bitten later when the calling function happens to sleep when it is not > @@ -233,6 +235,25 @@ extern void __cant_sleep(const char *file, int line, int preempt_offset); > # define cant_sleep() \ > do { __cant_sleep(__FILE__, __LINE__, 0); } while (0) > # define sched_annotate_sleep() (current->task_state_change = 0) > +/** > + * non_block_start - annotate the start of section where sleeping is prohibited > + * > + * This is on behalf of the oom reaper, specifically when it is calling the mmu > + * notifiers. The problem is that if the notifier were to block on, for example, > + * mutex_lock() and if the process which holds that mutex were to perform a > + * sleeping memory allocation, the oom reaper is now blocked on completion of > + * that memory allocation. Other blocking calls like wait_event() pose similar > + * issues. > + */ > +# define non_block_start() \ > + do { current->non_block_count++; } while (0) > +/** > + * non_block_end - annotate the end of section where sleeping is prohibited > + * > + * Closes a section opened by non_block_start(). > + */ > +# define non_block_end() \ > + do { WARN_ON(current->non_block_count-- == 0); } while (0) check-patch does not like these, and I agree #101: FILE: include/linux/kernel.h:248: +# define non_block_start() \ + do { current->non_block_count++; } while (0) /tmp/tmp1spfxufy/0006-kernel-h-Add-non_block_start-end-.patch:108: WARNING: Single statement macros should not use a do {} while (0) loop #108: FILE: include/linux/kernel.h:255: +# define non_block_end() \ + do { WARN_ON(current->non_block_count-- == 0); } while (0) Please use a static inline? Also, can we get one more ack on this patch? Jason