| Message ID | 20210309030605.3295183-1-zhengyejian1@huawei.com |
|---|---|
| Headers | show |
| Series | Backport patch series to update Futex from 4.9 | expand |
On Tue, Mar 09, 2021 at 11:06:05AM +0800, Zheng Yejian wrote: > From: Thomas Gleixner <tglx@linutronix.de> > > The handle_exit_race() function is defined in commit 9c3f39860367 > ("futex: Cure exit race"), which never returns -EBUSY. This results > in a small piece of dead code in the attach_to_pi_owner() function: > > int ret = handle_exit_race(uaddr, uval, p); /* Never return -EBUSY */ > ... > if (ret == -EBUSY) > *exiting = p; /* dead code */ > > The return value -EBUSY is added to handle_exit_race() in upsteam > commit ac31c7ff8624409 ("futex: Provide distinct return value when > owner is exiting"). This commit was incorporated into v4.9.255, before > the function handle_exit_race() was introduced, whitout Modify > handle_exit_race(). > > To fix dead code, extract the change of handle_exit_race() from > commit ac31c7ff8624409 ("futex: Provide distinct return value when owner > is exiting"), re-incorporated. > > Lee writes: > > This commit takes the remaining functional snippet of: > > ac31c7ff8624409 ("futex: Provide distinct return value when owner is exiting") > > ... and is the correct fix for this issue. > > Fixes: 9c3f39860367 ("futex: Cure exit race") > Cc: stable@vger.kernel.org # v4.9.258 > Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com> > Reviewed-by: Lee Jones <lee.jones@linaro.org> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com> > --- > kernel/futex.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) Same here, what is the upstream git id? thanks, greg k-h
On Tue, 09 Mar 2021, Greg KH wrote: > On Tue, Mar 09, 2021 at 11:06:05AM +0800, Zheng Yejian wrote: > > From: Thomas Gleixner <tglx@linutronix.de> > > > > The handle_exit_race() function is defined in commit 9c3f39860367 > > ("futex: Cure exit race"), which never returns -EBUSY. This results > > in a small piece of dead code in the attach_to_pi_owner() function: > > > > int ret = handle_exit_race(uaddr, uval, p); /* Never return -EBUSY */ > > ... > > if (ret == -EBUSY) > > *exiting = p; /* dead code */ > > > > The return value -EBUSY is added to handle_exit_race() in upsteam > > commit ac31c7ff8624409 ("futex: Provide distinct return value when > > owner is exiting"). This commit was incorporated into v4.9.255, before > > the function handle_exit_race() was introduced, whitout Modify > > handle_exit_race(). > > > > To fix dead code, extract the change of handle_exit_race() from > > commit ac31c7ff8624409 ("futex: Provide distinct return value when owner > > is exiting"), re-incorporated. > > > > Lee writes: > > > > This commit takes the remaining functional snippet of: > > > > ac31c7ff8624409 ("futex: Provide distinct return value when owner is exiting") > > > > ... and is the correct fix for this issue. > > > > Fixes: 9c3f39860367 ("futex: Cure exit race") > > Cc: stable@vger.kernel.org # v4.9.258 > > Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com> > > Reviewed-by: Lee Jones <lee.jones@linaro.org> > > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com> > > --- > > kernel/futex.c | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > Same here, what is the upstream git id? It doesn't have one as such - it's a part-patch: > > This commit takes the remaining functional snippet of: > > > > ac31c7ff8624409 ("futex: Provide distinct return value when owner is exiting")
On Tue, Mar 09, 2021 at 06:14:37PM +0000, Lee Jones wrote: > On Tue, 09 Mar 2021, Greg KH wrote: > > > On Tue, Mar 09, 2021 at 11:06:05AM +0800, Zheng Yejian wrote: > > > From: Thomas Gleixner <tglx@linutronix.de> > > > > > > The handle_exit_race() function is defined in commit 9c3f39860367 > > > ("futex: Cure exit race"), which never returns -EBUSY. This results > > > in a small piece of dead code in the attach_to_pi_owner() function: > > > > > > int ret = handle_exit_race(uaddr, uval, p); /* Never return -EBUSY */ > > > ... > > > if (ret == -EBUSY) > > > *exiting = p; /* dead code */ > > > > > > The return value -EBUSY is added to handle_exit_race() in upsteam > > > commit ac31c7ff8624409 ("futex: Provide distinct return value when > > > owner is exiting"). This commit was incorporated into v4.9.255, before > > > the function handle_exit_race() was introduced, whitout Modify > > > handle_exit_race(). > > > > > > To fix dead code, extract the change of handle_exit_race() from > > > commit ac31c7ff8624409 ("futex: Provide distinct return value when owner > > > is exiting"), re-incorporated. > > > > > > Lee writes: > > > > > > This commit takes the remaining functional snippet of: > > > > > > ac31c7ff8624409 ("futex: Provide distinct return value when owner is exiting") > > > > > > ... and is the correct fix for this issue. > > > > > > Fixes: 9c3f39860367 ("futex: Cure exit race") > > > Cc: stable@vger.kernel.org # v4.9.258 > > > Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com> > > > Reviewed-by: Lee Jones <lee.jones@linaro.org> > > > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > > Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com> > > > --- > > > kernel/futex.c | 6 +++--- > > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > Same here, what is the upstream git id? > > It doesn't have one as such - it's a part-patch: > > > > This commit takes the remaining functional snippet of: > > > > > > ac31c7ff8624409 ("futex: Provide distinct return value when owner is exiting") That wasn't obvious :( Is this a backport of another patch in the stable tree somewhere? confused, greg k-h
On Wed, 10 Mar 2021, Greg KH wrote: > On Tue, Mar 09, 2021 at 06:14:37PM +0000, Lee Jones wrote: > > On Tue, 09 Mar 2021, Greg KH wrote: > > > > > On Tue, Mar 09, 2021 at 11:06:05AM +0800, Zheng Yejian wrote: > > > > From: Thomas Gleixner <tglx@linutronix.de> > > > > > > > > The handle_exit_race() function is defined in commit 9c3f39860367 > > > > ("futex: Cure exit race"), which never returns -EBUSY. This results > > > > in a small piece of dead code in the attach_to_pi_owner() function: > > > > > > > > int ret = handle_exit_race(uaddr, uval, p); /* Never return -EBUSY */ > > > > ... > > > > if (ret == -EBUSY) > > > > *exiting = p; /* dead code */ > > > > > > > > The return value -EBUSY is added to handle_exit_race() in upsteam > > > > commit ac31c7ff8624409 ("futex: Provide distinct return value when > > > > owner is exiting"). This commit was incorporated into v4.9.255, before > > > > the function handle_exit_race() was introduced, whitout Modify > > > > handle_exit_race(). > > > > > > > > To fix dead code, extract the change of handle_exit_race() from > > > > commit ac31c7ff8624409 ("futex: Provide distinct return value when owner > > > > is exiting"), re-incorporated. > > > > > > > > Lee writes: > > > > > > > > This commit takes the remaining functional snippet of: > > > > > > > > ac31c7ff8624409 ("futex: Provide distinct return value when owner is exiting") > > > > > > > > ... and is the correct fix for this issue. > > > > > > > > Fixes: 9c3f39860367 ("futex: Cure exit race") > > > > Cc: stable@vger.kernel.org # v4.9.258 > > > > Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com> > > > > Reviewed-by: Lee Jones <lee.jones@linaro.org> > > > > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > > > Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com> > > > > --- > > > > kernel/futex.c | 6 +++--- > > > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > > > Same here, what is the upstream git id? > > > > It doesn't have one as such - it's a part-patch: > > > > > > This commit takes the remaining functional snippet of: > > > > > > > > ac31c7ff8624409 ("futex: Provide distinct return value when owner is exiting") > > That wasn't obvious :( This was also my thinking, which is why I replied to the original patch in an attempt to clarify what I thought was happening. > Is this a backport of another patch in the stable tree somewhere? Yes, it looks like it. The full patch was back-ported to v4.14 as: e6e00df182908f34360c3c9f2d13cc719362e9c0 -- Lee Jones [李琼斯] Senior Technical Lead - Developer Services Linaro.org │ Open source software for Arm SoCs Follow Linaro: Facebook | Twitter | Blog
On Wed, Mar 10, 2021 at 01:28:02PM +0000, Lee Jones wrote: > On Wed, 10 Mar 2021, Greg KH wrote: > > > On Tue, Mar 09, 2021 at 06:14:37PM +0000, Lee Jones wrote: > > > On Tue, 09 Mar 2021, Greg KH wrote: > > > > > > > On Tue, Mar 09, 2021 at 11:06:05AM +0800, Zheng Yejian wrote: > > > > > From: Thomas Gleixner <tglx@linutronix.de> > > > > > > > > > > The handle_exit_race() function is defined in commit 9c3f39860367 > > > > > ("futex: Cure exit race"), which never returns -EBUSY. This results > > > > > in a small piece of dead code in the attach_to_pi_owner() function: > > > > > > > > > > int ret = handle_exit_race(uaddr, uval, p); /* Never return -EBUSY */ > > > > > ... > > > > > if (ret == -EBUSY) > > > > > *exiting = p; /* dead code */ > > > > > > > > > > The return value -EBUSY is added to handle_exit_race() in upsteam > > > > > commit ac31c7ff8624409 ("futex: Provide distinct return value when > > > > > owner is exiting"). This commit was incorporated into v4.9.255, before > > > > > the function handle_exit_race() was introduced, whitout Modify > > > > > handle_exit_race(). > > > > > > > > > > To fix dead code, extract the change of handle_exit_race() from > > > > > commit ac31c7ff8624409 ("futex: Provide distinct return value when owner > > > > > is exiting"), re-incorporated. > > > > > > > > > > Lee writes: > > > > > > > > > > This commit takes the remaining functional snippet of: > > > > > > > > > > ac31c7ff8624409 ("futex: Provide distinct return value when owner is exiting") > > > > > > > > > > ... and is the correct fix for this issue. > > > > > > > > > > Fixes: 9c3f39860367 ("futex: Cure exit race") > > > > > Cc: stable@vger.kernel.org # v4.9.258 > > > > > Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com> > > > > > Reviewed-by: Lee Jones <lee.jones@linaro.org> > > > > > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > > > > Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com> > > > > > --- > > > > > kernel/futex.c | 6 +++--- > > > > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > > > > > Same here, what is the upstream git id? > > > > > > It doesn't have one as such - it's a part-patch: > > > > > > > > This commit takes the remaining functional snippet of: > > > > > > > > > > ac31c7ff8624409 ("futex: Provide distinct return value when owner is exiting") > > > > That wasn't obvious :( > > This was also my thinking, which is why I replied to the original > patch in an attempt to clarify what I thought was happening. > > > Is this a backport of another patch in the stable tree somewhere? > > Yes, it looks like it. > > The full patch was back-ported to v4.14 as: > > e6e00df182908f34360c3c9f2d13cc719362e9c0 Ok, Zheng, can you put this information in the patch and resend the whole series? thanks, greg k-h
On 2021/3/10 22:10, Greg KH wrote: > On Wed, Mar 10, 2021 at 01:28:02PM +0000, Lee Jones wrote: >> On Wed, 10 Mar 2021, Greg KH wrote: >> >>> On Tue, Mar 09, 2021 at 06:14:37PM +0000, Lee Jones wrote: >>>> On Tue, 09 Mar 2021, Greg KH wrote: >>>> >>>>> On Tue, Mar 09, 2021 at 11:06:05AM +0800, Zheng Yejian wrote: >>>>>> From: Thomas Gleixner <tglx@linutronix.de> >>>>>> >>>>>> The handle_exit_race() function is defined in commit 9c3f39860367 >>>>>> ("futex: Cure exit race"), which never returns -EBUSY. This results >>>>>> in a small piece of dead code in the attach_to_pi_owner() function: >>>>>> >>>>>> int ret = handle_exit_race(uaddr, uval, p); /* Never return -EBUSY */ >>>>>> ... >>>>>> if (ret == -EBUSY) >>>>>> *exiting = p; /* dead code */ >>>>>> >>>>>> The return value -EBUSY is added to handle_exit_race() in upsteam >>>>>> commit ac31c7ff8624409 ("futex: Provide distinct return value when >>>>>> owner is exiting"). This commit was incorporated into v4.9.255, before >>>>>> the function handle_exit_race() was introduced, whitout Modify >>>>>> handle_exit_race(). >>>>>> >>>>>> To fix dead code, extract the change of handle_exit_race() from >>>>>> commit ac31c7ff8624409 ("futex: Provide distinct return value when owner >>>>>> is exiting"), re-incorporated. >>>>>> >>>>>> Lee writes: >>>>>> >>>>>> This commit takes the remaining functional snippet of: >>>>>> >>>>>> ac31c7ff8624409 ("futex: Provide distinct return value when owner is exiting") >>>>>> >>>>>> ... and is the correct fix for this issue. >>>>>> >>>>>> Fixes: 9c3f39860367 ("futex: Cure exit race") >>>>>> Cc: stable@vger.kernel.org # v4.9.258 >>>>>> Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com> >>>>>> Reviewed-by: Lee Jones <lee.jones@linaro.org> >>>>>> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> >>>>>> Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com> >>>>>> --- >>>>>> kernel/futex.c | 6 +++--- >>>>>> 1 file changed, 3 insertions(+), 3 deletions(-) >>>>> >>>>> Same here, what is the upstream git id? >>>> >>>> It doesn't have one as such - it's a part-patch: >>>> >>>>>> This commit takes the remaining functional snippet of: >>>>>> >>>>>> ac31c7ff8624409 ("futex: Provide distinct return value when owner is exiting") >>> >>> That wasn't obvious :( >> >> This was also my thinking, which is why I replied to the original >> patch in an attempt to clarify what I thought was happening. >> >>> Is this a backport of another patch in the stable tree somewhere? >> >> Yes, it looks like it. >> >> The full patch was back-ported to v4.14 as: >> >> e6e00df182908f34360c3c9f2d13cc719362e9c0 > > Ok, Zheng, can you put this information in the patch and resend the > whole series? > Sure, I'll send a "v2" patchset soon. Thanks for your suggestions, Zheng Yejian
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.