linux-kernel - [PATCH 4.14 168/193] powerpc/64s/hash: Fix 512T hint detection to use >= 128T

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Message-Id: <20171128100621.469269236@linuxfoundation.org>
Date:   Tue, 28 Nov 2017 11:26:55 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Nicholas Piggin <npiggin@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>
Subject: [PATCH 4.14 168/193] powerpc/64s/hash: Fix 512T hint detection to use >= 128T

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Michael Ellerman <mpe@...erman.id.au>

commit 7ece370996b694ae263025e056ad785afc1be5ab upstream.

Currently userspace is able to request mmap() search between 128T-512T
by specifying a hint address that is greater than 128T. But that means
a hint of 128T exactly will return an address below 128T, which is
confusing and wrong.

So fix the logic to check the hint is greater than *or equal* to 128T.

Fixes: f4ea6dcb08ea ("powerpc/mm: Enable mappings above 128TB")
Suggested-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>
Suggested-by: Nicholas Piggin <npiggin@...il.com>
[mpe: Split out of Nick's bigger patch]
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/powerpc/mm/slice.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/powerpc/mm/slice.c
+++ b/arch/powerpc/mm/slice.c
@@ -419,7 +419,7 @@ unsigned long slice_get_unmapped_area(un
 	/*
 	 * Check if we need to expland slice area.
 	 */
-	if (unlikely(addr > mm->context.addr_limit &&
+	if (unlikely(addr >= mm->context.addr_limit &&
 		     mm->context.addr_limit != TASK_SIZE)) {
 		mm->context.addr_limit = TASK_SIZE;
 		on_each_cpu(slice_flush_segments, mm, 1);
@@ -427,7 +427,7 @@ unsigned long slice_get_unmapped_area(un
 	/*
 	 * This mmap request can allocate upt to 512TB
 	 */
-	if (addr > DEFAULT_MAP_WINDOW)
+	if (addr >= DEFAULT_MAP_WINDOW)
 		high_limit = mm->context.addr_limit;
 	else
 		high_limit = DEFAULT_MAP_WINDOW;