From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8E394C432C0 for ; Wed, 27 Nov 2019 14:23:19 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3F38920674 for ; Wed, 27 Nov 2019 14:23:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="WmRJHuHh" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3F38920674 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id E3CA16B04A1; Wed, 27 Nov 2019 09:23:18 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id E13BC6B04A2; Wed, 27 Nov 2019 09:23:18 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D2A116B04A3; Wed, 27 Nov 2019 09:23:18 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0076.hostedemail.com [216.40.44.76]) by kanga.kvack.org (Postfix) with ESMTP id BD10B6B04A1 for ; Wed, 27 Nov 2019 09:23:18 -0500 (EST) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id 72C5E8249980 for ; Wed, 27 Nov 2019 14:23:18 +0000 (UTC) X-FDA: 76202274876.27.tree29_5703776d4990b X-HE-Tag: tree29_5703776d4990b X-Filterd-Recvd-Size: 7588 Received: from mail-oi1-f194.google.com (mail-oi1-f194.google.com [209.85.167.194]) by imf03.hostedemail.com (Postfix) with ESMTP for ; Wed, 27 Nov 2019 14:23:17 +0000 (UTC) Received: by mail-oi1-f194.google.com with SMTP id k196so3858834oib.2 for ; Wed, 27 Nov 2019 06:23:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=SOR9n5ef3S18dZL/D+DU+eauySm2fm0XAf+d+UEl3ZQ=; b=WmRJHuHhdLrxOXv8Klx5qVBQLcGbwhRgitukBncW28KIm840xgcOyhUh63aK323W6y c/z0aHIRNeoJ8s5+8BKiaCTgjitMT2I+lKY8eGZuQ2mt42qvS4UwXnCYP57UnJ/GhPti U2aqkXtsFNvpiLsszFRBL296Rm4nc1rgSgfJZFdRsXHKSwKArQeqCwEDNRqFc0sjiULc 4H9TXt61yM2whgfLeUZ/PXDLOFUNcytNWBLOAY4FaT0D0cXpwxiQ8xiNltoKQbg+y9zD QaY0zytlRM1WtNxS47XxX8I7QtQqlijIUhgbPOJEtIzwXdKoZH9qDfh/ifLfInTcOx6D iprw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=SOR9n5ef3S18dZL/D+DU+eauySm2fm0XAf+d+UEl3ZQ=; b=KEqe/uxLSxqWy2QNPqKlOBKpjpFlPd74v8zfrFmfXNwgEpS6aM+HMyHRyeVhSYssLs O/MQO2fW5oETZTrIEIPS/ClifViDKlP3G0nVMgMxrdtQNEY6p6lFGylipr+vDHUV3lFm gO1BVvICtsYc0Wydh75UU+5sTvfpYnW3Mosuj0mvzXbW8u+D1X69pimRPGJJXjbLxLmm B9idV2fWtpj4zXAOloQetk/u9IPfTpB02o24moMVsyrREECA2Az3UOE8yAgeigMbkvzn yBttJpW1Pf/ndUALITpfos+zTibbI1Mbk9V5XIsYw1Du0Pl+cxncsr54ARINE+tE68Kw kF8w== X-Gm-Message-State: APjAAAVEzCQfnCrDqzRhqV2BEGMvFNJu90FkUc6eE3zDl6D7MFJFm1Ms qBNAM37H+21ITi5I+a+TOrAN4BGPaTBbe8Qhl2CpFg== X-Google-Smtp-Source: APXvYqwkai40mtSErFszAN2cJCu66f/7Z29yA4HNvX5HYHdLxXKrGfPQL8M/41enu7oOEgWzetgAJks0DX+k/tD3bQM= X-Received: by 2002:aca:d4c1:: with SMTP id l184mr4407663oig.172.1574864596717; Wed, 27 Nov 2019 06:23:16 -0800 (PST) MIME-Version: 1.0 References: <20191122112621.204798-1-glider@google.com> <20191122112621.204798-5-glider@google.com> In-Reply-To: <20191122112621.204798-5-glider@google.com> From: Marco Elver Date: Wed, 27 Nov 2019 15:23:05 +0100 Message-ID: Subject: Re: [PATCH RFC v3 04/36] stackdepot: reserve 5 extra bits in depot_stack_handle_t To: Alexander Potapenko Cc: Vegard Nossum , Dmitry Vyukov , Linux Memory Management List , Al Viro , adilger.kernel@dilger.ca, Andrew Morton , Andrey Konovalov , Andrey Ryabinin , Andy Lutomirski , Ard Biesheuvel , Arnd Bergmann , hch@infradead.org, hch@lst.de, darrick.wong@oracle.com, davem@davemloft.net, dmitry.torokhov@gmail.com, ebiggers@google.com, Eric Dumazet , ericvh@gmail.com, gregkh@linuxfoundation.org, harry.wentland@amd.com, herbert@gondor.apana.org.au, iii@linux.ibm.com, mingo@elte.hu, jasowang@redhat.com, axboe@kernel.dk, m.szyprowski@samsung.com, Mark Rutland , martin.petersen@oracle.com, schwidefsky@de.ibm.com, Matthew Wilcox , mst@redhat.com, monstr@monstr.eu, pmladek@suse.com, Qian Cai , Randy Dunlap , robin.murphy@arm.com, Sergey Senozhatsky , Steven Rostedt , tiwai@suse.com, tytso@mit.edu, Thomas Gleixner , gor@linux.ibm.com, wsa@the-dreams.de Content-Type: text/plain; charset="UTF-8" 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: On Fri, 22 Nov 2019 at 12:26, wrote: [...] > diff --git a/include/linux/stackdepot.h b/include/linux/stackdepot.h > index 24d49c732341..ac1b5a78d7f6 100644 > --- a/include/linux/stackdepot.h > +++ b/include/linux/stackdepot.h > @@ -12,6 +12,11 @@ > #define _LINUX_STACKDEPOT_H > > typedef u32 depot_stack_handle_t; > +/* > + * Number of bits in the handle that stack depot doesn't use. Users may store > + * information in them. > + */ > +#define STACK_DEPOT_EXTRA_BITS 5 > > depot_stack_handle_t stack_depot_save(unsigned long *entries, > unsigned int nr_entries, gfp_t gfp_flags); > @@ -20,5 +25,8 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle, > unsigned long **entries); > > unsigned int filter_irq_stacks(unsigned long *entries, unsigned int nr_entries); > +depot_stack_handle_t set_dsh_extra_bits(depot_stack_handle_t handle, > + unsigned int bits); The function declaration mismatches its definition ('unsigned bits' vs 'u32'). > +unsigned int get_dsh_extra_bits(depot_stack_handle_t handle); This also doesn't match the definition. The abbreviation 'dsh' in these function names is not very readable. Maybe just '{set,get}_stack_depot_extra' ? > #endif > diff --git a/lib/stackdepot.c b/lib/stackdepot.c > index eb95197b8743..e2f000a9fad8 100644 > --- a/lib/stackdepot.c > +++ b/lib/stackdepot.c > @@ -40,8 +40,10 @@ > #define STACK_ALLOC_ALIGN 4 > #define STACK_ALLOC_OFFSET_BITS (STACK_ALLOC_ORDER + PAGE_SHIFT - \ > STACK_ALLOC_ALIGN) > + > #define STACK_ALLOC_INDEX_BITS (DEPOT_STACK_BITS - \ > - STACK_ALLOC_NULL_PROTECTION_BITS - STACK_ALLOC_OFFSET_BITS) > + STACK_ALLOC_NULL_PROTECTION_BITS - \ > + STACK_ALLOC_OFFSET_BITS - STACK_DEPOT_EXTRA_BITS) > #define STACK_ALLOC_SLABS_CAP 8192 > #define STACK_ALLOC_MAX_SLABS \ > (((1LL << (STACK_ALLOC_INDEX_BITS)) < STACK_ALLOC_SLABS_CAP) ? \ > @@ -54,6 +56,7 @@ union handle_parts { > u32 slabindex : STACK_ALLOC_INDEX_BITS; > u32 offset : STACK_ALLOC_OFFSET_BITS; > u32 valid : STACK_ALLOC_NULL_PROTECTION_BITS; > + u32 extra : STACK_DEPOT_EXTRA_BITS; Would a BUILD_BUG_ON somewhere to assert that the total bits do not exceed DEPOT_STACK_BITS make sense? > }; > }; > > @@ -72,6 +75,24 @@ static int next_slab_inited; > static size_t depot_offset; > static DEFINE_SPINLOCK(depot_lock); > > +depot_stack_handle_t set_dsh_extra_bits(depot_stack_handle_t handle, > + u32 bits) > +{ > + union handle_parts parts = { .handle = handle }; > + > + parts.extra = bits & ((1U << STACK_DEPOT_EXTRA_BITS) - 1); > + return parts.handle; > +} > +EXPORT_SYMBOL_GPL(set_dsh_extra_bits); > + > +u32 get_dsh_extra_bits(depot_stack_handle_t handle) > +{ > + union handle_parts parts = { .handle = handle }; > + > + return parts.extra; > +} > +EXPORT_SYMBOL_GPL(get_dsh_extra_bits); > + > static bool init_stack_slab(void **prealloc) > { > if (!*prealloc) > @@ -132,6 +153,7 @@ static struct stack_record *depot_alloc_stack(unsigned long *entries, int size, > stack->handle.slabindex = depot_index; > stack->handle.offset = depot_offset >> STACK_ALLOC_ALIGN; > stack->handle.valid = 1; > + stack->handle.extra = 0; > memcpy(stack->entries, entries, size * sizeof(unsigned long)); > depot_offset += required_size; > > -- > 2.24.0.432.g9d3f5f5b63-goog >