linux-kernel - [PATCH 5/5] powerpc/32: reuse orphaned memblocks in kasan_init_shadow_page

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Message-Id: <b29ffffb9206dc14541fa420c17604240728041b.1579024426.git.christophe.leroy@c-s.fr>
Date:   Tue, 14 Jan 2020 17:54:04 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>, erhard_f@...lbox.org,
        dja@...ens.net
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH 5/5] powerpc/32: reuse orphaned memblocks in
 kasan_init_shadow_page_tables()

If concurrent PMD population has happened, re-use orphaned memblocks.

Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
---
 arch/powerpc/mm/kasan/kasan_init_32.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/mm/kasan/kasan_init_32.c b/arch/powerpc/mm/kasan/kasan_init_32.c
index c4bf9ed04f88..d3cacd462560 100644
--- a/arch/powerpc/mm/kasan/kasan_init_32.c
+++ b/arch/powerpc/mm/kasan/kasan_init_32.c
@@ -34,17 +34,17 @@ static int __init kasan_init_shadow_page_tables(unsigned long k_start, unsigned
 {
 	pmd_t *pmd;
 	unsigned long k_cur, k_next;
+	pte_t *new = NULL;
 
 	pmd = pmd_offset(pud_offset(pgd_offset_k(k_start), k_start), k_start);
 
 	for (k_cur = k_start; k_cur != k_end; k_cur = k_next, pmd++) {
-		pte_t *new;
-
 		k_next = pgd_addr_end(k_cur, k_end);
 		if ((void *)pmd_page_vaddr(*pmd) != kasan_early_shadow_pte)
 			continue;
 
-		new = memblock_alloc(PTE_FRAG_SIZE, PTE_FRAG_SIZE);
+		if (!new)
+			new = memblock_alloc(PTE_FRAG_SIZE, PTE_FRAG_SIZE);
 
 		if (!new)
 			return -ENOMEM;
-- 
2.13.3