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From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: rostedt <rostedt@goodmis.org>,
	Peter Zijlstra <peterz@infradead.org>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Boqun Feng <boqun.feng@gmail.com>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	linux-api <linux-api@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Andy Lutomirski <luto@amacapital.net>,
	Dave Watson <davejwatson@fb.com>, Paul Turner <pjt@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Russell King <linux@arm.linux.org.uk>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	Andi Kleen <andi@firstfloor.org>, Chris Lameter <cl@linux.com>,
	Ben Maurer <bmaurer@fb.com>,
	Josh Triplett <josh@joshtriplett.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Michael Kerrisk <mtk.manpages@gmail.com>,
	Joel Fernandes <joelaf@google.com>
Subject: Re: [RFC PATCH for 4.21 04/16] mm: Introduce vm_map_user_ram, vm_unmap_user_ram
Date: Wed, 17 Oct 2018 11:00:01 -0400 (EDT)
Message-ID: <1051015468.759.1539788401096.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <20181017002722.GA1068@jagdpanzerIV>

----- On Oct 16, 2018, at 8:27 PM, Sergey Senozhatsky sergey.senozhatsky.work@gmail.com wrote:

> On (10/16/18 14:30), Steven Rostedt wrote:
>> > +void vm_unmap_user_ram(const void *mem, unsigned int count)
>> > +{
>> > +	unsigned long size = (unsigned long)count << PAGE_SHIFT;
>> > +	unsigned long addr = (unsigned long)mem;
>> > +	struct vmap_area *va;
>> > +
>> > +	might_sleep();
>> > +	BUG_ON(!addr);
>> > +	BUG_ON(addr < VMALLOC_START);
>> > +	BUG_ON(addr > VMALLOC_END);
>> > +	BUG_ON(!PAGE_ALIGNED(addr));
>> > +
>> > +	debug_check_no_locks_freed(mem, size);
>> > +	va = find_vmap_area(addr);
>> > +	BUG_ON(!va);
>> > +	free_unmap_vmap_area(va);
>> > +}
>> > +EXPORT_SYMBOL(vm_unmap_user_ram);
>> > +
>> 
>> Noticing this from Sergey's question in another patch, why are you
>> using BUG_ON()? That's rather extreme and something we are trying to
>> avoid adding more of (I still need to remove the BUG_ON()s I've added
>> over ten years ago). I don't see why all these BUG_ON's can't be turned
>> into:
> 
> +1
> 
>> 	if (WARN_ON(x))
>> 		return;
> 
> Given that this somewhat MM-related, I'd may be say VM_WARN_ON().

Good point, will do!

So I'll do one cleanup patch for vm_unmap_ram(), and I'll modify the new vm_unmap_user_ram().

Thanks,

Mathieu

> 
> 	-ss

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com

  reply index

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-10 19:19 [RFC PATCH for 4.21 00/16] rseq updates, new cpu_opv system call Mathieu Desnoyers
2018-10-10 19:19 ` [RFC PATCH for 4.21 01/16] rseq/selftests: Add reference counter to coexist with glibc Mathieu Desnoyers
2018-10-11 10:37   ` Szabolcs Nagy
2018-10-11 15:13     ` Mathieu Desnoyers
2018-10-11 16:20       ` Szabolcs Nagy
2018-10-11 16:37         ` Mathieu Desnoyers
2018-10-11 17:04           ` Szabolcs Nagy
2018-10-11 19:42             ` Mathieu Desnoyers
2018-10-12  9:59               ` Szabolcs Nagy
2018-10-23 14:59                 ` Mathieu Desnoyers
2018-10-10 19:19 ` [RFC PATCH for 4.21 02/16] rseq/selftests: Adapt number of threads to the number of detected cpus Mathieu Desnoyers
2018-10-10 19:19 ` [RFC PATCH for 4.21 03/16] sched: Implement push_task_to_cpu (v2) Mathieu Desnoyers
2018-10-17  6:51   ` Srikar Dronamraju
2018-10-17 15:09     ` Mathieu Desnoyers
2018-10-10 19:19 ` [RFC PATCH for 4.21 04/16] mm: Introduce vm_map_user_ram, vm_unmap_user_ram Mathieu Desnoyers
2018-10-16 18:30   ` Steven Rostedt
2018-10-16 19:21     ` Mathieu Desnoyers
2018-10-16 19:40       ` Steven Rostedt
2018-10-17  0:27     ` Sergey Senozhatsky
2018-10-17 15:00       ` Mathieu Desnoyers [this message]
2018-10-17 15:04         ` Mathieu Desnoyers
2018-10-17 15:34           ` Sergey Senozhatsky
2018-10-10 19:19 ` [RFC PATCH for 4.21 05/16] mm: Provide is_vma_noncached Mathieu Desnoyers
2018-10-10 19:19 ` [RFC PATCH for 4.21 06/16] cpu_opv: Provide cpu_opv system call (v8) Mathieu Desnoyers
2018-10-16  8:10   ` Sergey Senozhatsky
2018-10-16 19:17     ` Mathieu Desnoyers
2018-10-17  1:46       ` Sergey Senozhatsky
2018-10-17  7:19   ` Srikar Dronamraju
2018-10-17 15:11     ` Mathieu Desnoyers
2018-10-17 16:09       ` Mathieu Desnoyers
2018-10-10 19:19 ` [RFC PATCH for 4.21 07/16] cpu_opv: limit amount of virtual address space used by cpu_opv Mathieu Desnoyers
2018-10-10 19:19 ` [RFC PATCH for 4.21 08/16] x86: Wire up cpu_opv system call Mathieu Desnoyers
2018-10-10 19:19 ` [RFC PATCH for 4.21 09/16] powerpc: " Mathieu Desnoyers
2018-10-10 19:19 ` [RFC PATCH for 4.21 10/16] arm: " Mathieu Desnoyers
2018-10-10 19:19 ` [RFC PATCH for 4.21 11/16] cpu-opv/selftests: Provide cpu-op library Mathieu Desnoyers
2018-10-10 19:19 ` [RFC PATCH for 4.21 12/16] cpu-opv/selftests: Provide basic test Mathieu Desnoyers
2018-10-10 19:19 ` [RFC PATCH for 4.21 13/16] cpu-opv/selftests: Provide percpu_op API Mathieu Desnoyers
2018-10-10 19:19 ` [RFC PATCH for 4.21 14/16] cpu-opv/selftests: Provide basic percpu ops test Mathieu Desnoyers
2018-10-10 19:19 ` [RFC PATCH for 4.21 15/16] cpu-opv/selftests: Provide parametrized tests Mathieu Desnoyers
2018-10-10 19:19 ` [RFC PATCH for 4.21 16/16] cpu-opv/selftests: Provide Makefile, scripts, gitignore Mathieu Desnoyers

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