From: Rick Lindsley <ricklind@linux.vnet.ibm.com>
To: Michael Ellerman <michaele@au1.ibm.com>, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH] powerpc/book3s/64: check for NULL pointer in pgd_alloc()
Date: Sun, 5 May 2019 17:20:43 -0700 [thread overview]
Message-ID: <5ae0401c-a84a-1e59-5d9d-70659f5a85de@linux.vnet.ibm.com> (raw)
When the memset code was added to pgd_alloc(), it failed to consider that kmem_cache_alloc() can return NULL. It's uncommon, but not impossible under heavy memory contention.
Signed-off-by: Rick Lindsley <ricklind@vnet.linux.ibm.com>
Fixes: cf266dbcd2a7 ("Zero PGD pages on allocation")
--- a/arch/powerpc/include/asm/book3s/64/pgalloc.h
+++ b/arch/powerpc/include/asm/book3s/64/pgalloc.h
@@ -81,6 +81,10 @@ static inline pgd_t *pgd_alloc(struct mm
pgd = kmem_cache_alloc(PGT_CACHE(PGD_INDEX_SIZE),
pgtable_gfp_flags(mm, GFP_KERNEL));
+
+ if (unlikely(!pgd))
+ return pgd;
+
/*
* Don't scan the PGD for pointers, it contains references to PUDs but
* those references are not full pointers and so can't be recognised by
next reply other threads:[~2019-05-06 0:22 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-06 0:20 Rick Lindsley [this message]
2019-05-06 11:33 ` [PATCH] powerpc/book3s/64: check for NULL pointer in pgd_alloc() Michael Ellerman
2019-05-06 16:43 ` Rick Lindsley
2019-05-09 15:34 ` Michael Ellerman
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