linux-kernel - [PATCH v2 3/5] mremap: don't do mm_populate(new

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Message-ID: <20150701230308.GA18031@redhat.com>
Date:	Thu, 2 Jul 2015 01:03:08 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Benjamin LaHaise <bcrl@...ck.org>,
	David Rientjes <rientjes@...gle.com>,
	Hugh Dickins <hughd@...gle.com>,
	Jeff Moyer <jmoyer@...hat.com>,
	Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
	Pavel Emelyanov <xemul@...allels.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 3/5] mremap: don't do mm_populate(new_addr) on failure

move_vma() sets *locked even if move_page_tables() or ->mremap()
fails, change sys_mremap() to check "ret & ~PAGE_MASK".

I think we should simply remove the VM_LOCKED code in move_vma(),
that is why this patch doesn't change move_vma(). But this needs
more cleanups.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
Acked-by: David Rientjes <rientjes@...gle.com>
---
 mm/mremap.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/mm/mremap.c b/mm/mremap.c
index 3310378..7dcf7b4 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -578,8 +578,10 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
 		ret = move_vma(vma, addr, old_len, new_len, new_addr, &locked);
 	}
 out:
-	if (ret & ~PAGE_MASK)
+	if (ret & ~PAGE_MASK) {
 		vm_unacct_memory(charged);
+		locked = 0;
+	}
 	up_write(&current->mm->mmap_sem);
 	if (locked && new_len > old_len)
 		mm_populate(new_addr + old_len, new_len - old_len);
-- 
1.5.5.1

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