linux-kernel - Re: [PATCH] mm/debug: add a cast to u64 for atomic64

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Date:   Mon, 11 Mar 2019 12:21:05 +0000
From:   Jason Gunthorpe <jgg@...lanox.com>
To:     Qian Cai <cai@....pw>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "arnd@...db.de" <arnd@...db.de>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm/debug: add a cast to u64 for atomic64_read()

On Sun, Mar 10, 2019 at 08:58:15PM -0700, Davidlohr Bueso wrote:
> On Sun, 10 Mar 2019, Qian Cai wrote:
> 
> > atomic64_read() on ppc64le returns "long int", so fix the same way as
> > the commit d549f545e690 ("drm/virtio: use %llu format string form
> > atomic64_t") by adding a cast to u64, which makes it work on all arches.
> > 
> > In file included from ./include/linux/printk.h:7,
> >                 from ./include/linux/kernel.h:15,
> >                 from mm/debug.c:9:
> > mm/debug.c: In function 'dump_mm':
> > ./include/linux/kern_levels.h:5:18: warning: format '%llx' expects
> > argument of type 'long long unsigned int', but argument 19 has type
> > 'long int' [-Wformat=]
> > #define KERN_SOH "\001"  /* ASCII Start Of Header */
> >                  ^~~~~~
> > ./include/linux/kern_levels.h:8:20: note: in expansion of macro
> > 'KERN_SOH'
> > #define KERN_EMERG KERN_SOH "0" /* system is unusable */
> >                    ^~~~~~~~
> > ./include/linux/printk.h:297:9: note: in expansion of macro 'KERN_EMERG'
> >  printk(KERN_EMERG pr_fmt(fmt), ##__VA_ARGS__)
> >         ^~~~~~~~~~
> > mm/debug.c:133:2: note: in expansion of macro 'pr_emerg'
> >  pr_emerg("mm %px mmap %px seqnum %llu task_size %lu\n"
> >  ^~~~~~~~
> > mm/debug.c:140:17: note: format string is defined here
> >   "pinned_vm %llx data_vm %lx exec_vm %lx stack_vm %lx\n"
> >              ~~~^
> >              %lx
> > 
> > Fixes: 70f8a3ca68d3 ("mm: make mm->pinned_vm an atomic64 counter")
> > Signed-off-by: Qian Cai <cai@....pw>
> 
> Acked-by: Davidlohr Bueso <dbueso@...e.de>

Not saying this patch shouldn't go ahead..

But is there a special reason the atomic64*'s on ppc don't use the u64
type like other archs? Seems like a better thing to fix than adding
casts all over the place.

Jason