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[PATCH] arm64: Kconfig: Make SME depend on BROKEN for now

by Mark Rutland

Although support for SME was merged in v5.19, we've since uncovered a number of issues with the implementation, including issues which might corrupt the FPSIMD/SVE/SME state of arbitrary tasks. While there are patches to address some of these issues, ongoing review has highlighted additional functional problems, and more time is necessary to analyse and fix these. For now, mark SME as BROKEN in the hope that we can fix things properly in the near future. As SME is an OPTIONAL part of ARMv9.2+, and there is very little extant hardware, this should not adversely affect the vast majority of users. Signed-off-by: Mark Rutland <mark.rutland(a)arm.com> Cc: Ard Biesheuvel <ardb(a)kernel.org> Cc: Catalin Marinas <catalin.marinas(a)arm.com> Cc: Marc Zyngier <maz(a)kernel.org> Cc: Mark Brown <broonie(a)kernel.org> Cc: Will Deacon <will(a)kernel.org> Cc: <stable(a)vger.kernel.org> # 5.19 --- arch/arm64/Kconfig | 1 + 1 file changed, 1 insertion(+) Catalin, Will, if we take this, the minimal set of other fixes necessary for now is: * "arm64/sve: Discard stale CPU state when handling SVE traps" https://lore.kernel.org/linux-arm-kernel/20241030-arm64-fpsimd-foreign-flus… https://lore.kernel.org/linux-arm-kernel/ZypuQNhWHKut8mLl@J2N7QTR9R3.cambri… (already queued by Will in for-next/fixes) * "arm64: smccc: Remove broken support for SMCCCv1.3 SVE discard hint" https://lore.kernel.org/linux-arm-kernel/20241106160448.2712997-1-mark.rutl… Mark. diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 3e29b44d2d7bd..14cc81e154ee2 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -2213,6 +2213,7 @@ config ARM64_SME bool "ARM Scalable Matrix Extension support" default y depends on ARM64_SVE + depends on BROKEN help The Scalable Matrix Extension (SME) is an extension to the AArch64 execution state which utilises a substantial subset of the SVE -- 2.30.2

12 months

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[PATCH] mm: fix a possible null pointer dereference in setup_zone_pageset()

by Qiu-ji Chen

The function call alloc_percpu() returns a pointer to the memory address, but it hasn't been checked. Our static analysis tool indicates that null pointer dereference may exist in pointer zone->per_cpu_pageset. It is always safe to judge the null pointer before use. Signed-off-by: Qiu-ji Chen <chenqiuji666(a)gmail.com> Cc: stable(a)vger.kernel.org Fixes: 9420f89db2dd ("mm: move most of core MM initialization to mm/mm_init.c") --- mm/page_alloc.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 8afab64814dc..5deae1193dc3 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5703,8 +5703,14 @@ void __meminit setup_zone_pageset(struct zone *zone) /* Size may be 0 on !SMP && !NUMA */ if (sizeof(struct per_cpu_zonestat) > 0) zone->per_cpu_zonestats = alloc_percpu(struct per_cpu_zonestat); + if (!zone->per_cpu_pageset) + return; zone->per_cpu_pageset = alloc_percpu(struct per_cpu_pages); + if (!zone->per_cpu_pageset) { + free_percpu(zone->per_cpu_pageset); + return; + } for_each_possible_cpu(cpu) { struct per_cpu_pages *pcp; struct per_cpu_zonestat *pzstats; -- 2.34.1

12 months

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[PATCH v3 2/3] dt-bindings: display: adi,adv7533: Drop single lane support

by Biju Das

As per [1], ADV7535/7533 support only 2-, 3-, or 4-lane. Drop unsupported 1-lane from bindings. [1] https://www.analog.com/media/en/technical-documentation/data-sheets/ADV7535… Fixes: 1e4d58cd7f88 ("drm/bridge: adv7533: Create a MIPI DSI device") Cc: stable(a)vger.kernel.org Signed-off-by: Biju Das <biju.das.jz(a)bp.renesas.com> --- v3: * New patch. --- .../devicetree/bindings/display/bridge/adi,adv7533.yaml | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml b/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml index df20a3c9c744..ec89115c74e4 100644 --- a/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml +++ b/Documentation/devicetree/bindings/display/bridge/adi,adv7533.yaml @@ -90,7 +90,7 @@ properties: adi,dsi-lanes: description: Number of DSI data lanes connected to the DSI host. $ref: /schemas/types.yaml#/definitions/uint32 - enum: [ 1, 2, 3, 4 ] + enum: [ 2, 3, 4 ] "#sound-dai-cells": const: 0 -- 2.43.0

12 months

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[PATCH v3 3/3] drm: adv7511: Drop dsi single lane support

by Biju Das

As per [1], ADV7535/7533 support only 2-, 3-, or 4-lane. Drop unsupported 1-lane. [1] https://www.analog.com/media/en/technical-documentation/data-sheets/ADV7535… Fixes: 1e4d58cd7f88 ("drm/bridge: adv7533: Create a MIPI DSI device") Reported-by: Hien Huynh <hien.huynh.px(a)renesas.com> Cc: stable(a)vger.kernel.org Signed-off-by: Biju Das <biju.das.jz(a)bp.renesas.com> --- Changes in v3: - Updated commit header and description - Updated fixes tag - Dropped single lane support Changes in v2: - Added the tag "Cc: stable(a)vger.kernel.org" in the sign-off area. - Dropped Archit Taneja invalid Mail address --- drivers/gpu/drm/bridge/adv7511/adv7533.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/bridge/adv7511/adv7533.c b/drivers/gpu/drm/bridge/adv7511/adv7533.c index de55d687245a..ec360f8b7509 100644 --- a/drivers/gpu/drm/bridge/adv7511/adv7533.c +++ b/drivers/gpu/drm/bridge/adv7511/adv7533.c @@ -173,7 +173,7 @@ int adv7533_parse_dt(struct device_node *np, struct adv7511 *adv) of_property_read_u32(np, "adi,dsi-lanes", &num_lanes); - if (num_lanes < 1 || num_lanes > 4) + if (num_lanes < 2 || num_lanes > 4) return -EINVAL; adv->num_dsi_lanes = num_lanes; -- 2.43.0

12 months

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[PATCH v3 1/3] drm: adv7511: Fix use-after-free in adv7533_attach_dsi()

by Biju Das

The host_node pointer assigned and freed in adv7533_parse_dt() and later adv7533_attach_dsi() uses the same. Fix this issue by freeing the host_node in adv7533_attach_dsi() instead of adv7533_parse_dt(). Fixes: 1e4d58cd7f88 ("drm/bridge: adv7533: Create a MIPI DSI device") Cc: stable(a)vger.kernel.org Signed-off-by: Biju Das <biju.das.jz(a)bp.renesas.com> --- Changes in v3: - Replace __free construct with readable of_node_put(). Changes in v2: - Added the tag "Cc: stable(a)vger.kernel.org" in the sign-off area. - Dropped Archit Taneja invalid Mail address --- drivers/gpu/drm/bridge/adv7511/adv7533.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/gpu/drm/bridge/adv7511/adv7533.c b/drivers/gpu/drm/bridge/adv7511/adv7533.c index 4481489aaf5e..de55d687245a 100644 --- a/drivers/gpu/drm/bridge/adv7511/adv7533.c +++ b/drivers/gpu/drm/bridge/adv7511/adv7533.c @@ -143,6 +143,7 @@ int adv7533_attach_dsi(struct adv7511 *adv) }; host = of_find_mipi_dsi_host_by_node(adv->host_node); + of_node_put(adv->host_node); if (!host) return dev_err_probe(dev, -EPROBE_DEFER, "failed to find dsi host\n"); @@ -181,8 +182,6 @@ int adv7533_parse_dt(struct device_node *np, struct adv7511 *adv) if (!adv->host_node) return -ENODEV; - of_node_put(adv->host_node); - adv->use_timing_gen = !of_property_read_bool(np, "adi,disable-timing-generator"); -- 2.43.0

12 months

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[PATCH] usb: xhci: quirk for data loss in ISOC transfers

by Raju Rangoju

During the High-Speed Isochronous Audio transfers, xHCI controller on certain AMD platforms experiences momentary data loss. This results in Missed Service Errors (MSE) being generated by the xHCI. The root cause of the MSE is attributed to the ISOC OUT endpoint being omitted from scheduling. This can happen either when an IN endpoint with a 64ms service interval is pre-scheduled prior to the ISOC OUT endpoint or when the interval of the ISOC OUT endpoint is shorter than that of the IN endpoint. Consequently, the OUT service is neglected when an IN endpoint with a service interval exceeding 32ms is scheduled concurrently (every 64ms in this scenario). This issue is particularly seen on certain older AMD platforms. To mitigate this problem, it is recommended to adjust the service interval of the IN endpoint to exceed 32ms (interval 8). This adjustment ensures that the OUT endpoint will not be bypassed, even if a smaller interval value is utilized. Cc: stable(a)vger.kernel.org Signed-off-by: Raju Rangoju <Raju.Rangoju(a)amd.com> --- drivers/usb/host/xhci-mem.c | 5 +++++ drivers/usb/host/xhci-pci.c | 14 ++++++++++++++ drivers/usb/host/xhci.h | 1 + 3 files changed, 20 insertions(+) diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c index d2900197a49e..4892bb9afa6e 100644 --- a/drivers/usb/host/xhci-mem.c +++ b/drivers/usb/host/xhci-mem.c @@ -1426,6 +1426,11 @@ int xhci_endpoint_init(struct xhci_hcd *xhci, /* Periodic endpoint bInterval limit quirk */ if (usb_endpoint_xfer_int(&ep->desc) || usb_endpoint_xfer_isoc(&ep->desc)) { + if ((xhci->quirks & XHCI_LIMIT_ENDPOINT_INTERVAL_9) && + usb_endpoint_xfer_int(&ep->desc) && + interval >= 9) { + interval = 8; + } if ((xhci->quirks & XHCI_LIMIT_ENDPOINT_INTERVAL_7) && udev->speed >= USB_SPEED_HIGH && interval >= 7) { diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c index cb07cee9ed0c..a078e2e5517d 100644 --- a/drivers/usb/host/xhci-pci.c +++ b/drivers/usb/host/xhci-pci.c @@ -284,6 +284,20 @@ static void xhci_pci_quirks(struct device *dev, struct xhci_hcd *xhci) if (pdev->vendor == PCI_VENDOR_ID_NEC) xhci->quirks |= XHCI_NEC_HOST; + if (pdev->vendor == PCI_VENDOR_ID_AMD && + (pdev->device == 0x13ed || + pdev->device == 0x13ee || + pdev->device == 0x148c || + pdev->device == 0x15d4 || + pdev->device == 0x15d5 || + pdev->device == 0x15e0 || + pdev->device == 0x15e1 || + pdev->device == 0x15e5)) + xhci->quirks |= XHCI_LIMIT_ENDPOINT_INTERVAL_9; + + if (pdev->vendor == PCI_VENDOR_ID_ATI && pdev->device == 0x7316) + xhci->quirks |= XHCI_LIMIT_ENDPOINT_INTERVAL_9; + if (pdev->vendor == PCI_VENDOR_ID_AMD && xhci->hci_version == 0x96) xhci->quirks |= XHCI_AMD_0x96_HOST; diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h index f0fb696d5619..fa69f7ac09b5 100644 --- a/drivers/usb/host/xhci.h +++ b/drivers/usb/host/xhci.h @@ -1624,6 +1624,7 @@ struct xhci_hcd { #define XHCI_ZHAOXIN_HOST BIT_ULL(46) #define XHCI_WRITE_64_HI_LO BIT_ULL(47) #define XHCI_CDNS_SCTX_QUIRK BIT_ULL(48) +#define XHCI_LIMIT_ENDPOINT_INTERVAL_9 BIT_ULL(49) unsigned int num_active_eps; unsigned int limit_active_eps; -- 2.34.1

12 months

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FAILED: Patch "posix-cpu-timers: Clear TICK_DEP_BIT_POSIX_TIMER on clone" failed to apply to v6.6-stable tree

by Sasha Levin

The patch below does not apply to the v6.6-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>. Thanks, Sasha ------------------ original commit in Linus's tree ------------------ From b5413156bad91dc2995a5c4eab1b05e56914638a Mon Sep 17 00:00:00 2001 From: Benjamin Segall <bsegall(a)google.com> Date: Fri, 25 Oct 2024 18:35:35 -0700 Subject: [PATCH] posix-cpu-timers: Clear TICK_DEP_BIT_POSIX_TIMER on clone When cloning a new thread, its posix_cputimers are not inherited, and are cleared by posix_cputimers_init(). However, this does not clear the tick dependency it creates in tsk->tick_dep_mask, and the handler does not reach the code to clear the dependency if there were no timers to begin with. Thus if a thread has a cputimer running before clone/fork, all descendants will prevent nohz_full unless they create a cputimer of their own. Fix this by entirely clearing the tick_dep_mask in copy_process(). (There is currently no inherited state that needs a tick dependency) Process-wide timers do not have this problem because fork does not copy signal_struct as a baseline, it creates one from scratch. Fixes: b78783000d5c ("posix-cpu-timers: Migrate to use new tick dependency mask model") Signed-off-by: Ben Segall <bsegall(a)google.com> Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de> Reviewed-by: Frederic Weisbecker <frederic(a)kernel.org> Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/all/xm26o737bq8o.fsf@google.com --- include/linux/tick.h | 8 ++++++++ kernel/fork.c | 2 ++ 2 files changed, 10 insertions(+) diff --git a/include/linux/tick.h b/include/linux/tick.h index 72744638c5b0f..99c9c5a7252aa 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -251,12 +251,19 @@ static inline void tick_dep_set_task(struct task_struct *tsk, if (tick_nohz_full_enabled()) tick_nohz_dep_set_task(tsk, bit); } + static inline void tick_dep_clear_task(struct task_struct *tsk, enum tick_dep_bits bit) { if (tick_nohz_full_enabled()) tick_nohz_dep_clear_task(tsk, bit); } + +static inline void tick_dep_init_task(struct task_struct *tsk) +{ + atomic_set(&tsk->tick_dep_mask, 0); +} + static inline void tick_dep_set_signal(struct task_struct *tsk, enum tick_dep_bits bit) { @@ -290,6 +297,7 @@ static inline void tick_dep_set_task(struct task_struct *tsk, enum tick_dep_bits bit) { } static inline void tick_dep_clear_task(struct task_struct *tsk, enum tick_dep_bits bit) { } +static inline void tick_dep_init_task(struct task_struct *tsk) { } static inline void tick_dep_set_signal(struct task_struct *tsk, enum tick_dep_bits bit) { } static inline void tick_dep_clear_signal(struct signal_struct *signal, diff --git a/kernel/fork.c b/kernel/fork.c index 89ceb4a68af25..6fa9fe62e01e3 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -105,6 +105,7 @@ #include <linux/rseq.h> #include <uapi/linux/pidfd.h> #include <linux/pidfs.h> +#include <linux/tick.h> #include <asm/pgalloc.h> #include <linux/uaccess.h> @@ -2292,6 +2293,7 @@ __latent_entropy struct task_struct *copy_process( acct_clear_integrals(p); posix_cputimers_init(&p->posix_cputimers); + tick_dep_init_task(p); p->io_context = NULL; audit_set_context(p, NULL); -- 2.43.0

12 months

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FAILED: Patch "posix-cpu-timers: Clear TICK_DEP_BIT_POSIX_TIMER on clone" failed to apply to v5.15-stable tree

by Sasha Levin

The patch below does not apply to the v5.15-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>. Thanks, Sasha ------------------ original commit in Linus's tree ------------------ From b5413156bad91dc2995a5c4eab1b05e56914638a Mon Sep 17 00:00:00 2001 From: Benjamin Segall <bsegall(a)google.com> Date: Fri, 25 Oct 2024 18:35:35 -0700 Subject: [PATCH] posix-cpu-timers: Clear TICK_DEP_BIT_POSIX_TIMER on clone When cloning a new thread, its posix_cputimers are not inherited, and are cleared by posix_cputimers_init(). However, this does not clear the tick dependency it creates in tsk->tick_dep_mask, and the handler does not reach the code to clear the dependency if there were no timers to begin with. Thus if a thread has a cputimer running before clone/fork, all descendants will prevent nohz_full unless they create a cputimer of their own. Fix this by entirely clearing the tick_dep_mask in copy_process(). (There is currently no inherited state that needs a tick dependency) Process-wide timers do not have this problem because fork does not copy signal_struct as a baseline, it creates one from scratch. Fixes: b78783000d5c ("posix-cpu-timers: Migrate to use new tick dependency mask model") Signed-off-by: Ben Segall <bsegall(a)google.com> Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de> Reviewed-by: Frederic Weisbecker <frederic(a)kernel.org> Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/all/xm26o737bq8o.fsf@google.com --- include/linux/tick.h | 8 ++++++++ kernel/fork.c | 2 ++ 2 files changed, 10 insertions(+) diff --git a/include/linux/tick.h b/include/linux/tick.h index 72744638c5b0f..99c9c5a7252aa 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -251,12 +251,19 @@ static inline void tick_dep_set_task(struct task_struct *tsk, if (tick_nohz_full_enabled()) tick_nohz_dep_set_task(tsk, bit); } + static inline void tick_dep_clear_task(struct task_struct *tsk, enum tick_dep_bits bit) { if (tick_nohz_full_enabled()) tick_nohz_dep_clear_task(tsk, bit); } + +static inline void tick_dep_init_task(struct task_struct *tsk) +{ + atomic_set(&tsk->tick_dep_mask, 0); +} + static inline void tick_dep_set_signal(struct task_struct *tsk, enum tick_dep_bits bit) { @@ -290,6 +297,7 @@ static inline void tick_dep_set_task(struct task_struct *tsk, enum tick_dep_bits bit) { } static inline void tick_dep_clear_task(struct task_struct *tsk, enum tick_dep_bits bit) { } +static inline void tick_dep_init_task(struct task_struct *tsk) { } static inline void tick_dep_set_signal(struct task_struct *tsk, enum tick_dep_bits bit) { } static inline void tick_dep_clear_signal(struct signal_struct *signal, diff --git a/kernel/fork.c b/kernel/fork.c index 89ceb4a68af25..6fa9fe62e01e3 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -105,6 +105,7 @@ #include <linux/rseq.h> #include <uapi/linux/pidfd.h> #include <linux/pidfs.h> +#include <linux/tick.h> #include <asm/pgalloc.h> #include <linux/uaccess.h> @@ -2292,6 +2293,7 @@ __latent_entropy struct task_struct *copy_process( acct_clear_integrals(p); posix_cputimers_init(&p->posix_cputimers); + tick_dep_init_task(p); p->io_context = NULL; audit_set_context(p, NULL); -- 2.43.0

12 months

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FAILED: Patch "posix-cpu-timers: Clear TICK_DEP_BIT_POSIX_TIMER on clone" failed to apply to v5.10-stable tree

by Sasha Levin

The patch below does not apply to the v5.10-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>. Thanks, Sasha ------------------ original commit in Linus's tree ------------------ From b5413156bad91dc2995a5c4eab1b05e56914638a Mon Sep 17 00:00:00 2001 From: Benjamin Segall <bsegall(a)google.com> Date: Fri, 25 Oct 2024 18:35:35 -0700 Subject: [PATCH] posix-cpu-timers: Clear TICK_DEP_BIT_POSIX_TIMER on clone When cloning a new thread, its posix_cputimers are not inherited, and are cleared by posix_cputimers_init(). However, this does not clear the tick dependency it creates in tsk->tick_dep_mask, and the handler does not reach the code to clear the dependency if there were no timers to begin with. Thus if a thread has a cputimer running before clone/fork, all descendants will prevent nohz_full unless they create a cputimer of their own. Fix this by entirely clearing the tick_dep_mask in copy_process(). (There is currently no inherited state that needs a tick dependency) Process-wide timers do not have this problem because fork does not copy signal_struct as a baseline, it creates one from scratch. Fixes: b78783000d5c ("posix-cpu-timers: Migrate to use new tick dependency mask model") Signed-off-by: Ben Segall <bsegall(a)google.com> Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de> Reviewed-by: Frederic Weisbecker <frederic(a)kernel.org> Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/all/xm26o737bq8o.fsf@google.com --- include/linux/tick.h | 8 ++++++++ kernel/fork.c | 2 ++ 2 files changed, 10 insertions(+) diff --git a/include/linux/tick.h b/include/linux/tick.h index 72744638c5b0f..99c9c5a7252aa 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -251,12 +251,19 @@ static inline void tick_dep_set_task(struct task_struct *tsk, if (tick_nohz_full_enabled()) tick_nohz_dep_set_task(tsk, bit); } + static inline void tick_dep_clear_task(struct task_struct *tsk, enum tick_dep_bits bit) { if (tick_nohz_full_enabled()) tick_nohz_dep_clear_task(tsk, bit); } + +static inline void tick_dep_init_task(struct task_struct *tsk) +{ + atomic_set(&tsk->tick_dep_mask, 0); +} + static inline void tick_dep_set_signal(struct task_struct *tsk, enum tick_dep_bits bit) { @@ -290,6 +297,7 @@ static inline void tick_dep_set_task(struct task_struct *tsk, enum tick_dep_bits bit) { } static inline void tick_dep_clear_task(struct task_struct *tsk, enum tick_dep_bits bit) { } +static inline void tick_dep_init_task(struct task_struct *tsk) { } static inline void tick_dep_set_signal(struct task_struct *tsk, enum tick_dep_bits bit) { } static inline void tick_dep_clear_signal(struct signal_struct *signal, diff --git a/kernel/fork.c b/kernel/fork.c index 89ceb4a68af25..6fa9fe62e01e3 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -105,6 +105,7 @@ #include <linux/rseq.h> #include <uapi/linux/pidfd.h> #include <linux/pidfs.h> +#include <linux/tick.h> #include <asm/pgalloc.h> #include <linux/uaccess.h> @@ -2292,6 +2293,7 @@ __latent_entropy struct task_struct *copy_process( acct_clear_integrals(p); posix_cputimers_init(&p->posix_cputimers); + tick_dep_init_task(p); p->io_context = NULL; audit_set_context(p, NULL); -- 2.43.0

12 months

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FAILED: Patch "posix-cpu-timers: Clear TICK_DEP_BIT_POSIX_TIMER on clone" failed to apply to v5.4-stable tree

by Sasha Levin

The patch below does not apply to the v5.4-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>. Thanks, Sasha ------------------ original commit in Linus's tree ------------------ From b5413156bad91dc2995a5c4eab1b05e56914638a Mon Sep 17 00:00:00 2001 From: Benjamin Segall <bsegall(a)google.com> Date: Fri, 25 Oct 2024 18:35:35 -0700 Subject: [PATCH] posix-cpu-timers: Clear TICK_DEP_BIT_POSIX_TIMER on clone When cloning a new thread, its posix_cputimers are not inherited, and are cleared by posix_cputimers_init(). However, this does not clear the tick dependency it creates in tsk->tick_dep_mask, and the handler does not reach the code to clear the dependency if there were no timers to begin with. Thus if a thread has a cputimer running before clone/fork, all descendants will prevent nohz_full unless they create a cputimer of their own. Fix this by entirely clearing the tick_dep_mask in copy_process(). (There is currently no inherited state that needs a tick dependency) Process-wide timers do not have this problem because fork does not copy signal_struct as a baseline, it creates one from scratch. Fixes: b78783000d5c ("posix-cpu-timers: Migrate to use new tick dependency mask model") Signed-off-by: Ben Segall <bsegall(a)google.com> Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de> Reviewed-by: Frederic Weisbecker <frederic(a)kernel.org> Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/all/xm26o737bq8o.fsf@google.com --- include/linux/tick.h | 8 ++++++++ kernel/fork.c | 2 ++ 2 files changed, 10 insertions(+) diff --git a/include/linux/tick.h b/include/linux/tick.h index 72744638c5b0f..99c9c5a7252aa 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -251,12 +251,19 @@ static inline void tick_dep_set_task(struct task_struct *tsk, if (tick_nohz_full_enabled()) tick_nohz_dep_set_task(tsk, bit); } + static inline void tick_dep_clear_task(struct task_struct *tsk, enum tick_dep_bits bit) { if (tick_nohz_full_enabled()) tick_nohz_dep_clear_task(tsk, bit); } + +static inline void tick_dep_init_task(struct task_struct *tsk) +{ + atomic_set(&tsk->tick_dep_mask, 0); +} + static inline void tick_dep_set_signal(struct task_struct *tsk, enum tick_dep_bits bit) { @@ -290,6 +297,7 @@ static inline void tick_dep_set_task(struct task_struct *tsk, enum tick_dep_bits bit) { } static inline void tick_dep_clear_task(struct task_struct *tsk, enum tick_dep_bits bit) { } +static inline void tick_dep_init_task(struct task_struct *tsk) { } static inline void tick_dep_set_signal(struct task_struct *tsk, enum tick_dep_bits bit) { } static inline void tick_dep_clear_signal(struct signal_struct *signal, diff --git a/kernel/fork.c b/kernel/fork.c index 89ceb4a68af25..6fa9fe62e01e3 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -105,6 +105,7 @@ #include <linux/rseq.h> #include <uapi/linux/pidfd.h> #include <linux/pidfs.h> +#include <linux/tick.h> #include <asm/pgalloc.h> #include <linux/uaccess.h> @@ -2292,6 +2293,7 @@ __latent_entropy struct task_struct *copy_process( acct_clear_integrals(p); posix_cputimers_init(&p->posix_cputimers); + tick_dep_init_task(p); p->io_context = NULL; audit_set_context(p, NULL); -- 2.43.0

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