From: Catalin Marinas <catalin.marinas@arm.com>
To: Mike Rapoport <rppt@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
Peng Fan <peng.fan@nxp.com>,
"labbott@redhat.com" <labbott@redhat.com>,
"mhocko@suse.com" <mhocko@suse.com>,
"iamjoonsoo.kim@lge.com" <iamjoonsoo.kim@lge.com>,
"rppt@linux.vnet.ibm.com" <rppt@linux.vnet.ibm.com>,
"m.szyprowski@samsung.com" <m.szyprowski@samsung.com>,
"rdunlap@infradead.org" <rdunlap@infradead.org>,
"andreyknvl@google.com" <andreyknvl@google.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"van.freenix@gmail.com" <van.freenix@gmail.com>
Subject: Re: [PATCH] mm/cma: cma_declare_contiguous: correct err handling
Date: Tue, 26 Feb 2019 14:52:21 +0000 [thread overview]
Message-ID: <20190226145218.GA124603@arrakis.emea.arm.com> (raw)
In-Reply-To: <20190219174610.GA32749@rapoport-lnx>
On Tue, Feb 19, 2019 at 07:46:11PM +0200, Mike Rapoport wrote:
> On Tue, Feb 19, 2019 at 05:55:33PM +0100, Vlastimil Babka wrote:
> > On 2/14/19 9:38 PM, Andrew Morton wrote:
> > > On Thu, 14 Feb 2019 12:45:51 +0000 Peng Fan <peng.fan@nxp.com> wrote:
> > >
> > >> In case cma_init_reserved_mem failed, need to free the memblock allocated
> > >> by memblock_reserve or memblock_alloc_range.
> > >>
> > >> ...
> > >>
> > >> --- a/mm/cma.c
> > >> +++ b/mm/cma.c
> > >> @@ -353,12 +353,14 @@ int __init cma_declare_contiguous(phys_addr_t base,
> > >>
> > >> ret = cma_init_reserved_mem(base, size, order_per_bit, name, res_cma);
> > >> if (ret)
> > >> - goto err;
> > >> + goto free_mem;
> > >>
> > >> pr_info("Reserved %ld MiB at %pa\n", (unsigned long)size / SZ_1M,
> > >> &base);
> > >> return 0;
> > >>
> > >> +free_mem:
> > >> + memblock_free(base, size);
> > >> err:
> > >> pr_err("Failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M);
> > >> return ret;
> > >
> > > This doesn't look right to me. In the `fixed==true' case we didn't
> > > actually allocate anything and in the `fixed==false' case, the
> > > allocated memory is at `addr', not at `base'.
> >
> > I think it's ok as the fixed==true path has "memblock_reserve()", but
> > better leave this to the memblock maintainer :)
>
> As Peng Fan noted in the other e-mail, fixed==true has memblock_reserve()
> and fixed==false resets base = addr, so this is Ok.
>
> > There's also 'kmemleak_ignore_phys(addr)' which should probably be
> > undone (or not called at all) in the failure case. But it seems to be
> > missing from the fixed==true path?
>
> Well, memblock and kmemleak interaction does not seem to have clear
> semantics anyway. memblock_free() calls kmemleak_free_part_phys() which
> does not seem to care about ignored objects.
> As for the fixed==true path, memblock_reserve() does not register the area
> with kmemleak, so there would be no object to free in memblock_free().
> AFAIU, kmemleak simply ignores this.
Kmemleak is supposed to work with the memblock_{alloc,free} pair and it
ignores the memblock_reserve() as a memblock_alloc() implementation
detail. It is, however, tolerant to memblock_free() being called on a
sub-range or just a different range from a previous memblock_alloc(). So
the original patch looks fine to me. FWIW:
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
prev parent reply other threads:[~2019-02-26 14:52 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-14 12:45 [PATCH] mm/cma: cma_declare_contiguous: correct err handling Peng Fan
2019-02-14 20:38 ` Andrew Morton
2019-02-15 1:30 ` Peng Fan
2019-02-19 16:55 ` Vlastimil Babka
2019-02-19 17:46 ` Mike Rapoport
2019-02-22 12:55 ` Peng Fan
2019-02-26 11:11 ` Mike Rapoport
2019-02-26 14:52 ` Catalin Marinas [this message]
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