> -----Original Message----- > From: Mike Rapoport [mailto:rppt@xxxxxxxxxxxxx] > Sent: 2019年2月20日 1:46 > To: Vlastimil Babka <vbabka@xxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>; Peng Fan > <peng.fan@xxxxxxx>; labbott@xxxxxxxxxx; mhocko@xxxxxxxx; > iamjoonsoo.kim@xxxxxxx; rppt@xxxxxxxxxxxxxxxxxx; > m.szyprowski@xxxxxxxxxxx; rdunlap@xxxxxxxxxxxxx; > andreyknvl@xxxxxxxxxx; linux-mm@xxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > van.freenix@xxxxxxxxx; Catalin Marinas <catalin.marinas@xxxxxxx> > 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.fan@xxxxxxx> > 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.
