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    SubjectRe: [PATCH stable 4.14,4.19 1/1] mm: Fix page counter mismatch in shmem_mfill_atomic_pte
    On Tue, Aug 16, 2022 at 03:04:08PM +0800, mawupeng wrote:
    >
    >
    > On 2022/8/16 13:31, Greg KH wrote:
    > > On Tue, Aug 16, 2022 at 11:27:08AM +0800, mawupeng wrote:
    > >> Cc Greg
    > >
    > > Cc Greg for what? I have no context here at all as to what you want me
    > > to do..
    >
    > We found a bug related to memory cgroup counter in stable 4.14/4.19.
    > shmem_mfill_atomic_pte() wrongly called mem_cgroup_cancel_charge() in "success"
    > path, it should mem_cgroup_uncharge() to dec memory counter instead.
    > mem_cgroup_cancel_charge() should only be used if this transaction is
    > unsuccessful and mem_cgroup_uncharge() is used to do this if this transaction
    > succeed.
    >
    > Commit 3fea5a499d57 ("mm: memcontrol: convert page cache to a new mem_cgroup_charge() API")
    > in v5.8-rc1 change is charge/uncharge/cancel logic so don't have this
    > problem.
    >
    > This counter will underflow to negative maximum value and trigger oom to kill all
    > process include sshd and leave system unaccessible.
    >
    > The reason cc you is that we want to merge this bugfix into stable 4.14/4.19.

    <formletter>

    This is not the correct way to submit patches for inclusion in the
    stable kernel tree. Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
    for how to do this properly.

    </formletter>

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