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    SubjectRe: [PATCH AUTOSEL 4.19 11/29] binder: take read mode of mmap_sem in binder_alloc_free_page()
    On Fri, Aug 30, 2019 at 02:30:19AM -0500, Tyler Hicks wrote:
    > On 2019-08-30 08:29:10, Greg Kroah-Hartman wrote:
    > > On Thu, Aug 29, 2019 at 10:13:20AM -0500, Tyler Hicks wrote:
    > > > Hello, Sasha!
    > > >
    > > > On 2019-08-29 06:49:51, Sasha Levin wrote:
    > > > > From: Tyler Hicks <tyhicks@canonical.com>
    > > > >
    > > > > [ Upstream commit 60d4885710836595192c42d3e04b27551d30ec91 ]
    > > > >
    > > > > Restore the behavior of locking mmap_sem for reading in
    > > > > binder_alloc_free_page(), as was first done in commit 3013bf62b67a
    > > > > ("binder: reduce mmap_sem write-side lock"). That change was
    > > > > inadvertently reverted by commit 5cec2d2e5839 ("binder: fix race between
    > > > > munmap() and direct reclaim").
    > > > >
    > > > > In addition, change the name of the label for the error path to
    > > > > accurately reflect that we're taking the lock for reading.
    > > > >
    > > > > Backporting note: This fix is only needed when *both* of the commits
    > > > > mentioned above are applied. That's an unlikely situation since they
    > > > > both landed during the development of v5.1 but only one of them is
    > > > > targeted for stable.
    > > >
    > > > This patch isn't meant to be applied to 4.19 since commit 3013bf62b67a
    > > > ("binder: reduce mmap_sem write-side lock") was never brought back to
    > > > 4.19.
    > > >
    > > > Tyler
    > > >
    > > > >
    > > > > Fixes: 5cec2d2e5839 ("binder: fix race between munmap() and direct reclaim")
    > >
    > > But this commit is in 4.19.49
    >
    > That's correct but commit 3013bf62b67a isn't present in 4.19.y. See the
    > "Backporting note" above.

    Heh, I never read that part of the text, nevermind :)

    greg k-h

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