From: Brian Geffon <bgeffon@google.com>
To: Dmitry Safonov <dima@arista.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Dmitry Safonov <0x7f454c46@gmail.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Lutomirski <luto@kernel.org>,
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 <linux-mm@kvack.org>
Subject: Re: [PATCH 2/6] mm/mremap: For MREMAP_DONTUNMAP check security_vm_enough_memory_mm()
Date: Wed, 30 Dec 2020 07:43:42 -0800 [thread overview]
Message-ID: <CADyq12w0+ZA6nwJOtJJ-66vHuq4aWwQw22NOUymz7KQa9DXqHQ@mail.gmail.com> (raw)
In-Reply-To: <d25ad10c-6f67-8c11-18c3-0193b8ea14c4@arista.com>
Ah, you're right. This individual patch looks good to me.
Brian
On Mon, Dec 28, 2020 at 11:12 AM Dmitry Safonov <dima@arista.com> wrote:
>
> On 12/28/20 6:21 PM, Brian Geffon wrote:
> > This looks good to me with a small comment.
> >
> >> if (do_munmap(mm, old_addr, old_len, uf_unmap) < 0) {
> >> /* OOM: unable to split vma, just get accounts right */
> >> - if (vm_flags & VM_ACCOUNT)
> >> + if (vm_flags & VM_ACCOUNT && !(flags & MREMAP_DONTUNMAP))
> >> vm_acct_memory(new_len >> PAGE_SHIFT);
> >
> > Checking MREMAP_DONTUNMAP in the do_munmap path is unnecessary as
> > MREMAP_DONTUNMAP will have already returned by this point.
>
> In this code it is also used as err-path. In case move_page_tables()
> fails to move all page tables or .mremap() callback fails, the new VMA
> is unmapped.
>
> IOW, MREMAP_DONTUNMAP returns under:
> : if (unlikely(!err && (flags & MREMAP_DONTUNMAP))) {
>
> --
> Dima
next prev parent reply other threads:[~2020-12-30 15:44 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-13 1:34 [PATCH 0/6] mremap: move_vma() fixes Dmitry Safonov
2020-10-13 1:34 ` [PATCH 1/6] mm/mremap: Account memory on do_munmap() failure Dmitry Safonov
2020-10-13 1:34 ` [PATCH 2/6] mm/mremap: For MREMAP_DONTUNMAP check security_vm_enough_memory_mm() Dmitry Safonov
2020-12-28 18:21 ` Brian Geffon
2020-12-28 19:12 ` Dmitry Safonov
2020-12-30 15:43 ` Brian Geffon [this message]
2020-10-13 1:34 ` [PATCH 3/6] mremap: Don't allow MREMAP_DONTUNMAP on special_mappings and aio Dmitry Safonov
2020-12-28 18:03 ` Brian Geffon
2020-12-28 19:33 ` Dmitry Safonov
2020-12-28 19:43 ` Dmitry Safonov
2020-10-13 1:34 ` [PATCH 4/6] vm_ops: Rename .split() callback to .may_split() Dmitry Safonov
2020-10-13 1:34 ` [PATCH 5/6] mremap: Check if it's possible to split original vma Dmitry Safonov
2020-10-13 1:34 ` [PATCH 6/6] mm: Forbid splitting special mappings Dmitry Safonov
2021-01-22 12:58 ` Will Deacon
2021-01-22 13:00 ` Will Deacon
2021-01-22 19:52 ` Dmitry Safonov
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