Linux-stable-mirror August 2025

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1331 discussions

[PATCH 5.15.y 1/2] scsi: ufs: ufs-pci: Fix hibernate state transition for Intel MTL-like host controllers

by Adrian Hunter

From: Archana Patni <archana.patni(a)intel.com> commit 4428ddea832cfdb63e476eb2e5c8feb5d36057fe upstream. UFSHCD core disables the UIC completion interrupt when issuing UIC hibernation commands, and re-enables it afterwards if it was enabled to start with, refer ufshcd_uic_pwr_ctrl(). For Intel MTL-like host controllers, accessing the register to re-enable the interrupt disrupts the state transition. Use hibern8_notify variant operation to disable the interrupt during the entire hibernation, thereby preventing the disruption. Fixes: 4049f7acef3e ("scsi: ufs: ufs-pci: Add support for Intel MTL") Cc: stable(a)vger.kernel.org Signed-off-by: Archana Patni <archana.patni(a)intel.com> Link: https://lore.kernel.org/r/20250723165856.145750-2-adrian.hunter@intel.com Reviewed-by: Bart Van Assche <bvanassche(a)acm.org> Signed-off-by: Martin K. Petersen <martin.petersen(a)oracle.com> Signed-off-by: Adrian Hunter <adrian.hunter(a)intel.com> --- drivers/scsi/ufs/ufshcd-pci.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/drivers/scsi/ufs/ufshcd-pci.c b/drivers/scsi/ufs/ufshcd-pci.c index 0920530a72d2..11071c132c1d 100644 --- a/drivers/scsi/ufs/ufshcd-pci.c +++ b/drivers/scsi/ufs/ufshcd-pci.c @@ -203,6 +203,32 @@ static int ufs_intel_lkf_apply_dev_quirks(struct ufs_hba *hba) return ret; } +static void ufs_intel_ctrl_uic_compl(struct ufs_hba *hba, bool enable) +{ + u32 set = ufshcd_readl(hba, REG_INTERRUPT_ENABLE); + + if (enable) + set |= UIC_COMMAND_COMPL; + else + set &= ~UIC_COMMAND_COMPL; + ufshcd_writel(hba, set, REG_INTERRUPT_ENABLE); +} + +static void ufs_intel_mtl_h8_notify(struct ufs_hba *hba, + enum uic_cmd_dme cmd, + enum ufs_notify_change_status status) +{ + /* + * Disable UIC COMPL INTR to prevent access to UFSHCI after + * checking HCS.UPMCRS + */ + if (status == PRE_CHANGE && cmd == UIC_CMD_DME_HIBER_ENTER) + ufs_intel_ctrl_uic_compl(hba, false); + + if (status == POST_CHANGE && cmd == UIC_CMD_DME_HIBER_EXIT) + ufs_intel_ctrl_uic_compl(hba, true); +} + #define INTEL_ACTIVELTR 0x804 #define INTEL_IDLELTR 0x808 @@ -476,6 +502,7 @@ static struct ufs_hba_variant_ops ufs_intel_mtl_hba_vops = { .init = ufs_intel_mtl_init, .exit = ufs_intel_common_exit, .hce_enable_notify = ufs_intel_hce_enable_notify, + .hibern8_notify = ufs_intel_mtl_h8_notify, .link_startup_notify = ufs_intel_link_startup_notify, .resume = ufs_intel_resume, .device_reset = ufs_intel_device_reset, -- 2.48.1

4 months, 1 week

[PATCH v2] iommu/virtio: Make instance lookup robust

by Robin Murphy

Much like arm-smmu in commit 7d835134d4e1 ("iommu/arm-smmu: Make instance lookup robust"), virtio-iommu appears to have the same issue where iommu_device_register() makes the IOMMU instance visible to other API callers (including itself) straight away, but internally the instance isn't ready to recognise itself for viommu_probe_device() to work correctly until after viommu_probe() has returned. This matters a lot more now that bus_iommu_probe() has the DT/VIOT knowledge to probe client devices the way that was always intended. Tweak the lookup and initialisation in much the same way as for arm-smmu, to ensure that what we register is functional and ready to go. Cc: stable(a)vger.kernel.org Fixes: bcb81ac6ae3c ("iommu: Get DT/ACPI parsing into the proper probe path") Signed-off-by: Robin Murphy <robin.murphy(a)arm.com> --- v2: Of course generic bus_find_device_by_fwnode() didn't work, since it's dev->parent we need to check rather than dev itself, sigh... --- drivers/iommu/virtio-iommu.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c index 532db1de201b..b39d6f134ab2 100644 --- a/drivers/iommu/virtio-iommu.c +++ b/drivers/iommu/virtio-iommu.c @@ -998,8 +998,7 @@ static void viommu_get_resv_regions(struct device *dev, struct list_head *head) iommu_dma_get_resv_regions(dev, head); } -static const struct iommu_ops viommu_ops; -static struct virtio_driver virtio_iommu_drv; +static const struct bus_type *virtio_bus_type; static int viommu_match_node(struct device *dev, const void *data) { @@ -1008,8 +1007,9 @@ static int viommu_match_node(struct device *dev, const void *data) static struct viommu_dev *viommu_get_by_fwnode(struct fwnode_handle *fwnode) { - struct device *dev = driver_find_device(&virtio_iommu_drv.driver, NULL, - fwnode, viommu_match_node); + struct device *dev = bus_find_device(virtio_bus_type, NULL, fwnode, + viommu_match_node); + put_device(dev); return dev ? dev_to_virtio(dev)->priv : NULL; @@ -1160,6 +1160,9 @@ static int viommu_probe(struct virtio_device *vdev) if (!viommu) return -ENOMEM; + /* Borrow this for easy lookups later */ + virtio_bus_type = dev->bus; + spin_lock_init(&viommu->request_lock); ida_init(&viommu->domain_ids); viommu->dev = dev; @@ -1229,10 +1232,10 @@ static int viommu_probe(struct virtio_device *vdev) if (ret) goto err_free_vqs; - iommu_device_register(&viommu->iommu, &viommu_ops, parent_dev); - vdev->priv = viommu; + iommu_device_register(&viommu->iommu, &viommu_ops, parent_dev); + dev_info(dev, "input address: %u bits\n", order_base_2(viommu->geometry.aperture_end)); dev_info(dev, "page mask: %#llx\n", viommu->pgsize_bitmap); -- 2.39.2.101.g768bb238c484.dirty

4 months, 1 week

FAILED: patch "[PATCH] selftests: mptcp: pm: check flush doesn't reset limits" failed to apply to 5.15-stable tree

by gregkh＠linuxfoundation.org

4 months, 1 week

FAILED: patch "[PATCH] selftests: mptcp: pm: check flush doesn't reset limits" failed to apply to 6.1-stable tree

by gregkh＠linuxfoundation.org

4 months, 1 week

FAILED: patch "[PATCH] selftests: mptcp: pm: check flush doesn't reset limits" failed to apply to 6.6-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 452690be7de2f91cc0de68cb9e95252875b33503 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025082256-enable-reusable-fcbd@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 452690be7de2f91cc0de68cb9e95252875b33503 Mon Sep 17 00:00:00 2001 From: "Matthieu Baerts (NGI0)" <matttbe(a)kernel.org> Date: Fri, 15 Aug 2025 19:28:21 +0200 Subject: [PATCH] selftests: mptcp: pm: check flush doesn't reset limits This modification is linked to the parent commit where the received ADD_ADDR limit was accidentally reset when the endpoints were flushed. To validate that, the test is now flushing endpoints after having set new limits, and before checking them. The 'Fixes' tag here below is the same as the one from the previous commit: this patch here is not fixing anything wrong in the selftests, but it validates the previous fix for an issue introduced by this commit ID. Fixes: 01cacb00b35c ("mptcp: add netlink-based PM") Cc: stable(a)vger.kernel.org Reviewed-by: Mat Martineau <martineau(a)kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe(a)kernel.org> Link: https://patch.msgid.link/20250815-net-mptcp-misc-fixes-6-17-rc2-v1-3-521fe9… Signed-off-by: Jakub Kicinski <kuba(a)kernel.org> diff --git a/tools/testing/selftests/net/mptcp/pm_netlink.sh b/tools/testing/selftests/net/mptcp/pm_netlink.sh index 2e6648a2b2c0..ac7ec6f94023 100755 --- a/tools/testing/selftests/net/mptcp/pm_netlink.sh +++ b/tools/testing/selftests/net/mptcp/pm_netlink.sh @@ -198,6 +198,7 @@ set_limits 1 9 2>/dev/null check "get_limits" "${default_limits}" "subflows above hard limit" set_limits 8 8 +flush_endpoint ## to make sure it doesn't affect the limits check "get_limits" "$(format_limits 8 8)" "set limits" flush_endpoint

4 months, 1 week

FAILED: patch "[PATCH] cpuidle: governors: menu: Avoid selecting states with too" failed to apply to 5.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x 779b1a1cb13ae17028aeddb2fbbdba97357a1e15 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025082226-jab-press-6046@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 779b1a1cb13ae17028aeddb2fbbdba97357a1e15 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" <rafael.j.wysocki(a)intel.com> Date: Wed, 13 Aug 2025 12:25:58 +0200 Subject: [PATCH] cpuidle: governors: menu: Avoid selecting states with too much latency Occasionally, the exit latency of the idle state selected by the menu governor may exceed the PM QoS CPU wakeup latency limit. Namely, if the scheduler tick has been stopped already and predicted_ns is greater than the tick period length, the governor may return an idle state whose exit latency exceeds latency_req because that decision is made before checking the current idle state's exit latency. For instance, say that there are 3 idle states, 0, 1, and 2. For idle states 0 and 1, the exit latency is equal to the target residency and the values are 0 and 5 us, respectively. State 2 is deeper and has the exit latency and target residency of 200 us and 2 ms (which is greater than the tick period length), respectively. Say that predicted_ns is equal to TICK_NSEC and the PM QoS latency limit is 20 us. After the first two iterations of the main loop in menu_select(), idx becomes 1 and in the third iteration of it the target residency of the current state (state 2) is greater than predicted_ns. State 2 is not a polling one and predicted_ns is not less than TICK_NSEC, so the check on whether or not the tick has been stopped is done. Say that the tick has been stopped already and there are no imminent timers (that is, delta_tick is greater than the target residency of state 2). In that case, idx becomes 2 and it is returned immediately, but the exit latency of state 2 exceeds the latency limit. Address this issue by modifying the code to compare the exit latency of the current idle state (idle state i) with the latency limit before comparing its target residency with predicted_ns, which allows one more exit_latency_ns check that becomes redundant to be dropped. However, after the above change, latency_req cannot take the predicted_ns value any more, which takes place after commit 38f83090f515 ("cpuidle: menu: Remove iowait influence"), because it may cause a polling state to be returned prematurely. In the context of the previous example say that predicted_ns is 3000 and the PM QoS latency limit is still 20 us. Additionally, say that idle state 0 is a polling one. Moving the exit_latency_ns check before the target_residency_ns one causes the loop to terminate in the second iteration, before the target_residency_ns check, so idle state 0 will be returned even though previously state 1 would be returned if there were no imminent timers. For this reason, remove the assignment of the predicted_ns value to latency_req from the code. Fixes: 5ef499cd571c ("cpuidle: menu: Handle stopped tick more aggressively") Cc: 4.17+ <stable(a)vger.kernel.org> # 4.17+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki(a)intel.com> Reviewed-by: Christian Loehle <christian.loehle(a)arm.com> Link: https://patch.msgid.link/5043159.31r3eYUQgx@rafael.j.wysocki diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c index 81306612a5c6..b2e3d0b0a116 100644 --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -287,20 +287,15 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, return 0; } - if (tick_nohz_tick_stopped()) { - /* - * If the tick is already stopped, the cost of possible short - * idle duration misprediction is much higher, because the CPU - * may be stuck in a shallow idle state for a long time as a - * result of it. In that case say we might mispredict and use - * the known time till the closest timer event for the idle - * state selection. - */ - if (predicted_ns < TICK_NSEC) - predicted_ns = data->next_timer_ns; - } else if (latency_req > predicted_ns) { - latency_req = predicted_ns; - } + /* + * If the tick is already stopped, the cost of possible short idle + * duration misprediction is much higher, because the CPU may be stuck + * in a shallow idle state for a long time as a result of it. In that + * case, say we might mispredict and use the known time till the closest + * timer event for the idle state selection. + */ + if (tick_nohz_tick_stopped() && predicted_ns < TICK_NSEC) + predicted_ns = data->next_timer_ns; /* * Find the idle state with the lowest power while satisfying @@ -316,13 +311,15 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, if (idx == -1) idx = i; /* first enabled state */ + if (s->exit_latency_ns > latency_req) + break; + if (s->target_residency_ns > predicted_ns) { /* * Use a physical idle state, not busy polling, unless * a timer is going to trigger soon enough. */ if ((drv->states[idx].flags & CPUIDLE_FLAG_POLLING) && - s->exit_latency_ns <= latency_req && s->target_residency_ns <= data->next_timer_ns) { predicted_ns = s->target_residency_ns; idx = i; @@ -354,8 +351,6 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, return idx; } - if (s->exit_latency_ns > latency_req) - break; idx = i; }

4 months, 1 week

FAILED: patch "[PATCH] cpuidle: governors: menu: Avoid selecting states with too" failed to apply to 5.10-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x 779b1a1cb13ae17028aeddb2fbbdba97357a1e15 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025082225-daylight-confusing-9794@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 779b1a1cb13ae17028aeddb2fbbdba97357a1e15 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" <rafael.j.wysocki(a)intel.com> Date: Wed, 13 Aug 2025 12:25:58 +0200 Subject: [PATCH] cpuidle: governors: menu: Avoid selecting states with too much latency Occasionally, the exit latency of the idle state selected by the menu governor may exceed the PM QoS CPU wakeup latency limit. Namely, if the scheduler tick has been stopped already and predicted_ns is greater than the tick period length, the governor may return an idle state whose exit latency exceeds latency_req because that decision is made before checking the current idle state's exit latency. For instance, say that there are 3 idle states, 0, 1, and 2. For idle states 0 and 1, the exit latency is equal to the target residency and the values are 0 and 5 us, respectively. State 2 is deeper and has the exit latency and target residency of 200 us and 2 ms (which is greater than the tick period length), respectively. Say that predicted_ns is equal to TICK_NSEC and the PM QoS latency limit is 20 us. After the first two iterations of the main loop in menu_select(), idx becomes 1 and in the third iteration of it the target residency of the current state (state 2) is greater than predicted_ns. State 2 is not a polling one and predicted_ns is not less than TICK_NSEC, so the check on whether or not the tick has been stopped is done. Say that the tick has been stopped already and there are no imminent timers (that is, delta_tick is greater than the target residency of state 2). In that case, idx becomes 2 and it is returned immediately, but the exit latency of state 2 exceeds the latency limit. Address this issue by modifying the code to compare the exit latency of the current idle state (idle state i) with the latency limit before comparing its target residency with predicted_ns, which allows one more exit_latency_ns check that becomes redundant to be dropped. However, after the above change, latency_req cannot take the predicted_ns value any more, which takes place after commit 38f83090f515 ("cpuidle: menu: Remove iowait influence"), because it may cause a polling state to be returned prematurely. In the context of the previous example say that predicted_ns is 3000 and the PM QoS latency limit is still 20 us. Additionally, say that idle state 0 is a polling one. Moving the exit_latency_ns check before the target_residency_ns one causes the loop to terminate in the second iteration, before the target_residency_ns check, so idle state 0 will be returned even though previously state 1 would be returned if there were no imminent timers. For this reason, remove the assignment of the predicted_ns value to latency_req from the code. Fixes: 5ef499cd571c ("cpuidle: menu: Handle stopped tick more aggressively") Cc: 4.17+ <stable(a)vger.kernel.org> # 4.17+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki(a)intel.com> Reviewed-by: Christian Loehle <christian.loehle(a)arm.com> Link: https://patch.msgid.link/5043159.31r3eYUQgx@rafael.j.wysocki diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c index 81306612a5c6..b2e3d0b0a116 100644 --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -287,20 +287,15 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, return 0; } - if (tick_nohz_tick_stopped()) { - /* - * If the tick is already stopped, the cost of possible short - * idle duration misprediction is much higher, because the CPU - * may be stuck in a shallow idle state for a long time as a - * result of it. In that case say we might mispredict and use - * the known time till the closest timer event for the idle - * state selection. - */ - if (predicted_ns < TICK_NSEC) - predicted_ns = data->next_timer_ns; - } else if (latency_req > predicted_ns) { - latency_req = predicted_ns; - } + /* + * If the tick is already stopped, the cost of possible short idle + * duration misprediction is much higher, because the CPU may be stuck + * in a shallow idle state for a long time as a result of it. In that + * case, say we might mispredict and use the known time till the closest + * timer event for the idle state selection. + */ + if (tick_nohz_tick_stopped() && predicted_ns < TICK_NSEC) + predicted_ns = data->next_timer_ns; /* * Find the idle state with the lowest power while satisfying @@ -316,13 +311,15 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, if (idx == -1) idx = i; /* first enabled state */ + if (s->exit_latency_ns > latency_req) + break; + if (s->target_residency_ns > predicted_ns) { /* * Use a physical idle state, not busy polling, unless * a timer is going to trigger soon enough. */ if ((drv->states[idx].flags & CPUIDLE_FLAG_POLLING) && - s->exit_latency_ns <= latency_req && s->target_residency_ns <= data->next_timer_ns) { predicted_ns = s->target_residency_ns; idx = i; @@ -354,8 +351,6 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, return idx; } - if (s->exit_latency_ns > latency_req) - break; idx = i; }

4 months, 1 week

FAILED: patch "[PATCH] cpuidle: governors: menu: Avoid selecting states with too" failed to apply to 5.15-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 779b1a1cb13ae17028aeddb2fbbdba97357a1e15 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025082218-twine-jailhouse-91b9@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 779b1a1cb13ae17028aeddb2fbbdba97357a1e15 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" <rafael.j.wysocki(a)intel.com> Date: Wed, 13 Aug 2025 12:25:58 +0200 Subject: [PATCH] cpuidle: governors: menu: Avoid selecting states with too much latency Occasionally, the exit latency of the idle state selected by the menu governor may exceed the PM QoS CPU wakeup latency limit. Namely, if the scheduler tick has been stopped already and predicted_ns is greater than the tick period length, the governor may return an idle state whose exit latency exceeds latency_req because that decision is made before checking the current idle state's exit latency. For instance, say that there are 3 idle states, 0, 1, and 2. For idle states 0 and 1, the exit latency is equal to the target residency and the values are 0 and 5 us, respectively. State 2 is deeper and has the exit latency and target residency of 200 us and 2 ms (which is greater than the tick period length), respectively. Say that predicted_ns is equal to TICK_NSEC and the PM QoS latency limit is 20 us. After the first two iterations of the main loop in menu_select(), idx becomes 1 and in the third iteration of it the target residency of the current state (state 2) is greater than predicted_ns. State 2 is not a polling one and predicted_ns is not less than TICK_NSEC, so the check on whether or not the tick has been stopped is done. Say that the tick has been stopped already and there are no imminent timers (that is, delta_tick is greater than the target residency of state 2). In that case, idx becomes 2 and it is returned immediately, but the exit latency of state 2 exceeds the latency limit. Address this issue by modifying the code to compare the exit latency of the current idle state (idle state i) with the latency limit before comparing its target residency with predicted_ns, which allows one more exit_latency_ns check that becomes redundant to be dropped. However, after the above change, latency_req cannot take the predicted_ns value any more, which takes place after commit 38f83090f515 ("cpuidle: menu: Remove iowait influence"), because it may cause a polling state to be returned prematurely. In the context of the previous example say that predicted_ns is 3000 and the PM QoS latency limit is still 20 us. Additionally, say that idle state 0 is a polling one. Moving the exit_latency_ns check before the target_residency_ns one causes the loop to terminate in the second iteration, before the target_residency_ns check, so idle state 0 will be returned even though previously state 1 would be returned if there were no imminent timers. For this reason, remove the assignment of the predicted_ns value to latency_req from the code. Fixes: 5ef499cd571c ("cpuidle: menu: Handle stopped tick more aggressively") Cc: 4.17+ <stable(a)vger.kernel.org> # 4.17+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki(a)intel.com> Reviewed-by: Christian Loehle <christian.loehle(a)arm.com> Link: https://patch.msgid.link/5043159.31r3eYUQgx@rafael.j.wysocki diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c index 81306612a5c6..b2e3d0b0a116 100644 --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -287,20 +287,15 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, return 0; } - if (tick_nohz_tick_stopped()) { - /* - * If the tick is already stopped, the cost of possible short - * idle duration misprediction is much higher, because the CPU - * may be stuck in a shallow idle state for a long time as a - * result of it. In that case say we might mispredict and use - * the known time till the closest timer event for the idle - * state selection. - */ - if (predicted_ns < TICK_NSEC) - predicted_ns = data->next_timer_ns; - } else if (latency_req > predicted_ns) { - latency_req = predicted_ns; - } + /* + * If the tick is already stopped, the cost of possible short idle + * duration misprediction is much higher, because the CPU may be stuck + * in a shallow idle state for a long time as a result of it. In that + * case, say we might mispredict and use the known time till the closest + * timer event for the idle state selection. + */ + if (tick_nohz_tick_stopped() && predicted_ns < TICK_NSEC) + predicted_ns = data->next_timer_ns; /* * Find the idle state with the lowest power while satisfying @@ -316,13 +311,15 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, if (idx == -1) idx = i; /* first enabled state */ + if (s->exit_latency_ns > latency_req) + break; + if (s->target_residency_ns > predicted_ns) { /* * Use a physical idle state, not busy polling, unless * a timer is going to trigger soon enough. */ if ((drv->states[idx].flags & CPUIDLE_FLAG_POLLING) && - s->exit_latency_ns <= latency_req && s->target_residency_ns <= data->next_timer_ns) { predicted_ns = s->target_residency_ns; idx = i; @@ -354,8 +351,6 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, return idx; } - if (s->exit_latency_ns > latency_req) - break; idx = i; }

4 months, 1 week

FAILED: patch "[PATCH] cpuidle: governors: menu: Avoid selecting states with too" failed to apply to 6.1-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 779b1a1cb13ae17028aeddb2fbbdba97357a1e15 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025082217-sabbath-economist-f935@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 779b1a1cb13ae17028aeddb2fbbdba97357a1e15 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" <rafael.j.wysocki(a)intel.com> Date: Wed, 13 Aug 2025 12:25:58 +0200 Subject: [PATCH] cpuidle: governors: menu: Avoid selecting states with too much latency Occasionally, the exit latency of the idle state selected by the menu governor may exceed the PM QoS CPU wakeup latency limit. Namely, if the scheduler tick has been stopped already and predicted_ns is greater than the tick period length, the governor may return an idle state whose exit latency exceeds latency_req because that decision is made before checking the current idle state's exit latency. For instance, say that there are 3 idle states, 0, 1, and 2. For idle states 0 and 1, the exit latency is equal to the target residency and the values are 0 and 5 us, respectively. State 2 is deeper and has the exit latency and target residency of 200 us and 2 ms (which is greater than the tick period length), respectively. Say that predicted_ns is equal to TICK_NSEC and the PM QoS latency limit is 20 us. After the first two iterations of the main loop in menu_select(), idx becomes 1 and in the third iteration of it the target residency of the current state (state 2) is greater than predicted_ns. State 2 is not a polling one and predicted_ns is not less than TICK_NSEC, so the check on whether or not the tick has been stopped is done. Say that the tick has been stopped already and there are no imminent timers (that is, delta_tick is greater than the target residency of state 2). In that case, idx becomes 2 and it is returned immediately, but the exit latency of state 2 exceeds the latency limit. Address this issue by modifying the code to compare the exit latency of the current idle state (idle state i) with the latency limit before comparing its target residency with predicted_ns, which allows one more exit_latency_ns check that becomes redundant to be dropped. However, after the above change, latency_req cannot take the predicted_ns value any more, which takes place after commit 38f83090f515 ("cpuidle: menu: Remove iowait influence"), because it may cause a polling state to be returned prematurely. In the context of the previous example say that predicted_ns is 3000 and the PM QoS latency limit is still 20 us. Additionally, say that idle state 0 is a polling one. Moving the exit_latency_ns check before the target_residency_ns one causes the loop to terminate in the second iteration, before the target_residency_ns check, so idle state 0 will be returned even though previously state 1 would be returned if there were no imminent timers. For this reason, remove the assignment of the predicted_ns value to latency_req from the code. Fixes: 5ef499cd571c ("cpuidle: menu: Handle stopped tick more aggressively") Cc: 4.17+ <stable(a)vger.kernel.org> # 4.17+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki(a)intel.com> Reviewed-by: Christian Loehle <christian.loehle(a)arm.com> Link: https://patch.msgid.link/5043159.31r3eYUQgx@rafael.j.wysocki diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c index 81306612a5c6..b2e3d0b0a116 100644 --- a/drivers/cpuidle/governors/menu.c +++ b/drivers/cpuidle/governors/menu.c @@ -287,20 +287,15 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, return 0; } - if (tick_nohz_tick_stopped()) { - /* - * If the tick is already stopped, the cost of possible short - * idle duration misprediction is much higher, because the CPU - * may be stuck in a shallow idle state for a long time as a - * result of it. In that case say we might mispredict and use - * the known time till the closest timer event for the idle - * state selection. - */ - if (predicted_ns < TICK_NSEC) - predicted_ns = data->next_timer_ns; - } else if (latency_req > predicted_ns) { - latency_req = predicted_ns; - } + /* + * If the tick is already stopped, the cost of possible short idle + * duration misprediction is much higher, because the CPU may be stuck + * in a shallow idle state for a long time as a result of it. In that + * case, say we might mispredict and use the known time till the closest + * timer event for the idle state selection. + */ + if (tick_nohz_tick_stopped() && predicted_ns < TICK_NSEC) + predicted_ns = data->next_timer_ns; /* * Find the idle state with the lowest power while satisfying @@ -316,13 +311,15 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, if (idx == -1) idx = i; /* first enabled state */ + if (s->exit_latency_ns > latency_req) + break; + if (s->target_residency_ns > predicted_ns) { /* * Use a physical idle state, not busy polling, unless * a timer is going to trigger soon enough. */ if ((drv->states[idx].flags & CPUIDLE_FLAG_POLLING) && - s->exit_latency_ns <= latency_req && s->target_residency_ns <= data->next_timer_ns) { predicted_ns = s->target_residency_ns; idx = i; @@ -354,8 +351,6 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev, return idx; } - if (s->exit_latency_ns > latency_req) - break; idx = i; }

4 months, 1 week

FAILED: patch "[PATCH] ipv6: sr: Fix MAC comparison to be constant-time" failed to apply to 5.4-stable tree

by gregkh＠linuxfoundation.org

4 months, 1 week

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