Messages in this thread | | | Subject | Re: [PATCH 4.4 0/3] Backport patch series to update Futex from 4.9 | From | "Zhengyejian (Zetta)" <> | Date | Thu, 11 Mar 2021 11:48:52 +0800 |
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On 2021/3/9 18:41, Greg KH wrote: > On Tue, Mar 09, 2021 at 11:06:02AM +0800, Zheng Yejian wrote: >> Lee sent a patchset to update Futex for 4.9, see https://www.spinics.net/lists/stable/msg443081.html, >> Then Xiaoming sent a follow-up patch for it, see https://lore.kernel.org/lkml/20210225093120.GD641347@dell/. >> >> These patchsets may also resolve following issues in 4.4.260 which have been reported in 4.9, >> see https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/?h=linux-4.4.y&id=319f66f08de1083c1fe271261665c209009dd65a >> > /* >> > * The task is on the way out. When the futex state is >> > * FUTEX_STATE_DEAD, we know that the task has finished >> > * the cleanup: >> > */ >> > int ret = (p->futex_state = FUTEX_STATE_DEAD) ? -ESRCH : -EAGAIN; >> >> Here may be: >> int ret = (p->futex_state == FUTEX_STATE_DEAD) ? -ESRCH : -EAGAIN; >> >> > raw_spin_unlock_irq(&p->pi_lock); >> > /* >> > * If the owner task is between FUTEX_STATE_EXITING and >> > * FUTEX_STATE_DEAD then store the task pointer and keep >> > * the reference on the task struct. The calling code will >> > * drop all locks, wait for the task to reach >> > * FUTEX_STATE_DEAD and then drop the refcount. This is >> > * required to prevent a live lock when the current task >> > * preempted the exiting task between the two states. >> > */ >> > if (ret == -EBUSY) >> >> And here, the variable "ret" may only be "-ESRCH" or "-EAGAIN", but not "-EBUSY". >> >> > *exiting = p; >> > else >> > put_task_struct(p); >> >> Since 074e7d515783 ("futex: Ensure the correct return value from futex_lock_pi()") has >> been merged in 4.4.260, I send the remain 3 patches. > > There already are 2 futex patches in the 4.4.y stable queue, do those > not resolve these issues for you?
I think that 2 futex patches in 4.4 stable queue are fixing other issues: futex-fix-irq-self-deadlock-and-satisfy-assertion.patch futex-fix-spin_lock-spin_unlock_irq-imbalance.patch But I am not very sure if there are any lock conflicts between that 2 patches and this 3 patches.
> > If not, please resend this series with the needed git commit ids added to > them.
I have add that information and sent a "v2" patchset.
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