linux-kernel - [PATCH V2] mm/cma: cma_declare_contiguous: correct err handling

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Date:   Wed, 27 Feb 2019 14:34:55 +0000
From:   Peng Fan <peng.fan@....com>
To:     "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "labbott@...hat.com" <labbott@...hat.com>,
        "iamjoonsoo.kim@....com" <iamjoonsoo.kim@....com>,
        "mhocko@...e.com" <mhocko@...e.com>,
        "vbabka@...e.cz" <vbabka@...e.cz>,
        "rppt@...ux.vnet.ibm.com" <rppt@...ux.vnet.ibm.com>,
        "m.szyprowski@...sung.com" <m.szyprowski@...sung.com>,
        "andreyknvl@...gle.com" <andreyknvl@...gle.com>,
        "catalin.marinas@....com" <catalin.marinas@....com>
CC:     "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "van.freenix@...il.com" <van.freenix@...il.com>,
        Peng Fan <peng.fan@....com>
Subject: [PATCH V2] mm/cma: cma_declare_contiguous: correct err handling

In case cma_init_reserved_mem failed, need to free the memblock allocated
by memblock_reserve or memblock_alloc_range.

Quote Catalin's comments:
https://lkml.org/lkml/2019/2/26/482
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:

Signed-off-by: Peng Fan <peng.fan@....com>
Reviewed-by: Catalin Marinas <catalin.marinas@....com>
---

V2:
 Per Mike's comments, add more information in commit log
 Add R-B

 mm/cma.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/cma.c b/mm/cma.c
index c7b39dd3b4f6..f4f3a8a57d86 100644
--- 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;
-- 
2.16.4