> -----Original Message-----
> From: Mike Rapoport [mailto:r...@linux.ibm.com]
> Sent: 2019年2月20日 1:46
> To: Vlastimil Babka <vba...@suse.cz>
> Cc: Andrew Morton <a...@linux-foundation.org>; Peng Fan
> <peng....@nxp.com>; labb...@redhat.com; mho...@suse.com;
> iamjoonsoo....@lge.com; r...@linux.vnet.ibm.com;
> m.szyprow...@samsung.com; rdun...@infradead.org;
> andreyk...@google.com; linux...@kvack.org; linux-kernel@vger.kernel.org;
> van.free...@gmail.com; Catalin Marinas <catalin.mari...@arm.com>
> Subject: Re: [PATCH] mm/cma: cma_declare_contiguous: correct err handling
>
> 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....@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.
I also go through the memblock_free flow, and agree with Mike
memblock_free
-> kmemleak_free_part_phys
-> kmemleak_free_part
|-> delete_object_part
|-> object = find_and_remove_object(ptr, 1);
memblock_reserve not register the area in kmemleak, so find_and_remove_object
will not be able to find a valid area and just return.
What should I do next with this patch?
Thanks,
Peng.
>
> Catalin, can you comment please?
>
> --
> Sincerely yours,
> Mike.
