Linux SNPS ARC Archive on lore.kernel.org
 help / color / Atom feed
From: Anshuman Khandual <anshuman.khandual@arm.com>
To: Qian Cai <cai@lca.pw>, linux-mm@kvack.org
Cc: Mark Rutland <mark.rutland@arm.com>,
	linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org,
	Peter Zijlstra <peterz@infradead.org>,
	James Hogan <jhogan@kernel.org>,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	Michal Hocko <mhocko@kernel.org>,
	Dave Hansen <dave.hansen@intel.com>,
	Paul Mackerras <paulus@samba.org>,
	sparclinux@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
	linux-s390@vger.kernel.org, Jason Gunthorpe <jgg@ziepe.ca>,
	Michael Ellerman <mpe@ellerman.id.au>,
	x86@kernel.org, Russell King - ARM Linux <linux@armlinux.org.uk>,
	Matthew Wilcox <willy@infradead.org>,
	Steven Price <Steven.Price@arm.com>,
	Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	Gerald Schaefer <gerald.schaefer@de.ibm.com>,
	linux-snps-arc@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	Kees Cook <keescook@chromium.org>,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	Mark Brown <broonie@kernel.org>,
	"Kirill A . Shutemov" <kirill@shutemov.name>,
	Dan Williams <dan.j.williams@intel.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Christophe Leroy <christophe.leroy@c-s.fr>,
	Sri Krishna chowdary <schowdary@nvidia.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-mips@vger.kernel.org, Ralf Baechle <ralf@linux-mips.org>,
	linux-kernel@vger.kernel.org, Paul Burton <paul.burton@mips.com>,
	Mike Rapoport <rppt@linux.vnet.ibm.com>,
	Vineet Gupta <vgupta@synopsys.com>,
	Martin Schwidefsky <schwidefsky@de.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linuxppc-dev@lists.ozlabs.org,
	"David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH V6 2/2] mm/debug: Add tests validating architecture page table helpers
Date: Wed, 16 Oct 2019 15:24:23 +0530
Message-ID: <7cd03155-6713-3116-1e88-f81f84dd794f@arm.com> (raw)
In-Reply-To: <1571162982.5937.42.camel@lca.pw>



On 10/15/2019 11:39 PM, Qian Cai wrote:
> On Tue, 2019-10-15 at 14:51 +0530, Anshuman Khandual wrote:
>> +static unsigned long __init get_random_vaddr(void)
>> +{
>> +	unsigned long random_vaddr, random_pages, total_user_pages;
>> +
>> +	total_user_pages = (TASK_SIZE - FIRST_USER_ADDRESS) / PAGE_SIZE;
>> +
>> +	random_pages = get_random_long() % total_user_pages;
>> +	random_vaddr = FIRST_USER_ADDRESS + random_pages * PAGE_SIZE;
>> +
>> +	WARN_ON(random_vaddr > TASK_SIZE);
>> +	WARN_ON(random_vaddr < FIRST_USER_ADDRESS);
> 
> It would be nice if this patch does not introduce a new W=1 GCC warning here on
> x86 because FIRST_USER_ADDRESS is 0, and GCC think the code is dumb because
> "random_vaddr" is unsigned,
> 
> In file included from ./arch/x86/include/asm/bug.h:83,
>                  from ./include/linux/bug.h:5,
>                  from ./include/linux/mmdebug.h:5,
>                  from ./include/linux/gfp.h:5,
>                  from mm/debug_vm_pgtable.c:13:
> mm/debug_vm_pgtable.c: In function ‘get_random_vaddr’:
> mm/debug_vm_pgtable.c:359:23: warning: comparison of unsigned expression < 0 is
> always false [-Wtype-limits]
>   WARN_ON(random_vaddr < FIRST_USER_ADDRESS);
>                        ^
> ./include/asm-generic/bug.h:113:25: note: in definition of macro ‘WARN_ON’
>   int __ret_warn_on = !!(condition);    \
>                          ^~~~~~~~~

The test checks against an erroneous unsigned long overflow when
FIRST_USER_ADDRESS is not 0 but a positive number. Wondering if
the compiler will still complain if we merge both the WARN_ON()
checks as || on a single statement.

_______________________________________________
linux-snps-arc mailing list
linux-snps-arc@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-snps-arc

  reply index

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1571131302-32290-1-git-send-email-anshuman.khandual@arm.com>
     [not found] ` <1571131302-32290-2-git-send-email-anshuman.khandual@arm.com>
2019-10-15 10:45   ` [PATCH V6 1/2] mm/page_alloc: Make alloc_gigantic_page() available for general use Michal Hocko
2019-10-15 11:07     ` Anshuman Khandual
2019-10-15 11:42   ` David Hildenbrand
2019-10-15 11:47     ` Michal Hocko
2019-10-15 11:50       ` David Hildenbrand
2019-10-15 12:01         ` David Hildenbrand
2019-10-15 12:09         ` Michal Hocko
2019-10-15 12:11           ` Michal Hocko
     [not found] ` <1571131302-32290-3-git-send-email-anshuman.khandual@arm.com>
2019-10-15 11:46   ` [PATCH V6 2/2] mm/debug: Add tests validating architecture page table helpers Michal Hocko
2019-10-15 12:27     ` Anshuman Khandual
2019-10-15 18:09   ` Qian Cai
2019-10-16  9:54     ` Anshuman Khandual [this message]
2019-10-15 14:41 ` [PATCH V6 0/2] " Qian Cai
2019-10-15 15:21   ` Anshuman Khandual
2019-10-15 18:42     ` Qian Cai
2019-10-16  8:59       ` Anshuman Khandual
2019-10-16  8:20     ` Michal Hocko

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=7cd03155-6713-3116-1e88-f81f84dd794f@arm.com \
    --to=anshuman.khandual@arm.com \
    --cc=Steven.Price@arm.com \
    --cc=akpm@linux-foundation.org \
    --cc=ard.biesheuvel@linaro.org \
    --cc=broonie@kernel.org \
    --cc=cai@lca.pw \
    --cc=christophe.leroy@c-s.fr \
    --cc=dan.j.williams@intel.com \
    --cc=dave.hansen@intel.com \
    --cc=davem@davemloft.net \
    --cc=gerald.schaefer@de.ibm.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=heiko.carstens@de.ibm.com \
    --cc=jgg@ziepe.ca \
    --cc=jhogan@kernel.org \
    --cc=keescook@chromium.org \
    --cc=kirill@shutemov.name \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-ia64@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mips@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linux-s390@vger.kernel.org \
    --cc=linux-sh@vger.kernel.org \
    --cc=linux-snps-arc@lists.infradead.org \
    --cc=linux@armlinux.org.uk \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=mark.rutland@arm.com \
    --cc=mhocko@kernel.org \
    --cc=mpe@ellerman.id.au \
    --cc=paul.burton@mips.com \
    --cc=paulus@samba.org \
    --cc=penguin-kernel@i-love.sakura.ne.jp \
    --cc=peterz@infradead.org \
    --cc=ralf@linux-mips.org \
    --cc=rppt@linux.vnet.ibm.com \
    --cc=schowdary@nvidia.com \
    --cc=schwidefsky@de.ibm.com \
    --cc=sparclinux@vger.kernel.org \
    --cc=tglx@linutronix.de \
    --cc=vbabka@suse.cz \
    --cc=vgupta@synopsys.com \
    --cc=willy@infradead.org \
    --cc=x86@kernel.org \
    --cc=yamada.masahiro@socionext.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux SNPS ARC Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-snps-arc/0 linux-snps-arc/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-snps-arc linux-snps-arc/ https://lore.kernel.org/linux-snps-arc \
		linux-snps-arc@lists.infradead.org
	public-inbox-index linux-snps-arc

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.infradead.lists.linux-snps-arc


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git