[PATCH 1/6] mm/mremap: Account memory on do_munmap() failure

From: Dmitry Safonov <dima@arista.com>
To: linux-kernel@vger.kernel.org
Cc: Dmitry Safonov <0x7f454c46@gmail.com>,
	Dmitry Safonov <dima@arista.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andy Lutomirski <luto@kernel.org>,
	Brian Geffon <bgeffon@google.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Dave Jiang <dave.jiang@intel.com>,
	Hugh Dickins <hughd@google.com>, Ingo Molnar <mingo@redhat.com>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Minchan Kim <minchan@kernel.org>,
	Russell King <linux@armlinux.org.uk>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Vishal Verma <vishal.l.verma@intel.com>,
	Vlastimil Babka <vbabka@suse.cz>, Will Deacon <will@kernel.org>,
	linux-aio@kvack.org, linux-fsdevel@vger.kernel.org,
	linux-mm@kvack.org
Subject: [PATCH 1/6] mm/mremap: Account memory on do_munmap() failure
Date: Tue, 13 Oct 2020 02:34:11 +0100	[thread overview]
Message-ID: <20201013013416.390574-2-dima@arista.com> (raw)
In-Reply-To: <20201013013416.390574-1-dima@arista.com>

move_vma() copies VMA without adding it to account, then unmaps old part
of VMA. On failure it unmaps the new VMA. With hacks accounting in
munmap is disabled as it's a copy of existing VMA.

Account the memory on munmap() failure which was previously copied into
a new VMA.

Fixes: commit e2ea83742133 ("[PATCH] mremap: move_vma fixes and cleanup")
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 mm/mremap.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/mremap.c b/mm/mremap.c
index 138abbae4f75..03d31a0d4c67 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -450,7 +450,8 @@ static unsigned long move_vma(struct vm_area_struct *vma,
 
 	if (do_munmap(mm, old_addr, old_len, uf_unmap) < 0) {
 		/* OOM: unable to split vma, just get accounts right */
-		vm_unacct_memory(excess >> PAGE_SHIFT);
+		if (vm_flags & VM_ACCOUNT)
+			vm_acct_memory(new_len >> PAGE_SHIFT);
 		excess = 0;
 	}
 
-- 
2.28.0


