linux-kernel - [PATCH 4/4] mm,hugetlb: compute page_size

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Date:   Thu,  9 Feb 2017 12:53:02 -0800
From:   Davidlohr Bueso <dave@...olabs.net>
To:     akpm@...ux-foundation.org
Cc:     manfred@...orfullife.com, dave@...olabs.net,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Davidlohr Bueso <dbueso@...e.de>
Subject: [PATCH 4/4] mm,hugetlb: compute page_size_log properly

The SHM_HUGE_* stuff  was introduced in:

   42d7395feb5 (mm: support more pagesizes for MAP_HUGETLB/SHM_HUGETLB)

It unnecessarily adds another layer, specific to sysv shm, without
anything special about it: the macros are identical to the MAP_HUGE_*
stuff, which in turn does correctly describe the hugepage subsystem.

One example of the problems with extra layers what this patch fixes:
mmap_pgoff() should never be using SHM_HUGE_* logic. It is obviously
harmless but it would still be grand to get rid of it -- although
now in the manpages I don't see that happening.

Cc: linux-mm@...ck.org
Signed-off-by: Davidlohr Bueso <dbueso@...e.de>
---
 mm/mmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 499b988b1639..40b29aca18c1 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1479,7 +1479,7 @@ SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
 		struct user_struct *user = NULL;
 		struct hstate *hs;

-		hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & SHM_HUGE_MASK);
+		hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
 		if (!hs)
 			return -EINVAL;

-- 
2.6.6