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[PATCH OLK-5.10] livepatch/core: Fix possible issue that old function is not checked
by Zheng Yejian 07 Sep '23

07 Sep '23

hulk inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I7ZH67 CVE: NA -------------------------------- After patch being enabled, the first few instructions would be modified to jump to the new function, then callers of old function would jump to new function but always through the old function. Therefore when enabling a new patch or disable a patch on the old function, we should always consider that old function is running. Otherwise, there may be situations where old functions are being modified before jumping to new function and cause issues. Signed-off-by: Zheng Yejian <zhengyejian1(a)huawei.com> --- arch/arm/kernel/livepatch.c | 23 ++++++++++++++++++++--- arch/arm64/kernel/livepatch.c | 23 ++++++++++++++++++++--- arch/powerpc/kernel/livepatch_32.c | 22 +++++++++++++++++++--- arch/x86/kernel/livepatch.c | 23 +++++++++++++++++++---- 4 files changed, 78 insertions(+), 13 deletions(-) diff --git a/arch/arm/kernel/livepatch.c b/arch/arm/kernel/livepatch.c index b4d26474ba33..5415de07c8f7 100644 --- a/arch/arm/kernel/livepatch.c +++ b/arch/arm/kernel/livepatch.c @@ -134,11 +134,14 @@ static int klp_check_activeness_func(struct klp_patch *patch, int enable, struct klp_object *obj; struct klp_func_node *func_node; struct klp_func *func; - unsigned long func_addr, func_size; + unsigned long func_addr = 0; + unsigned long func_size; struct klp_func_list *pcheck = NULL; for (obj = patch->objs; obj->funcs; obj++) { for (func = obj->funcs; func->old_name; func++) { + unsigned long old_func = (unsigned long)func->old_func; + if (enable) { if (func->patched || func->force == KLP_ENFORCEMENT) continue; @@ -153,7 +156,7 @@ static int klp_check_activeness_func(struct klp_patch *patch, int enable, * No patched on this function * [ the origin one ] */ - func_addr = (unsigned long)func->old_func; + func_addr = old_func; func_size = func->old_size; } else { /* @@ -184,6 +187,13 @@ static int klp_check_activeness_func(struct klp_patch *patch, int enable, func->old_name, func->force); if (ret) return ret; + if (func_addr != old_func) { + ret = add_func_to_list(check_funcs, &pcheck, + old_func, func->old_size, + func->old_name, func->force); + if (ret) + return ret; + } } } else { /* @@ -203,7 +213,7 @@ static int klp_check_activeness_func(struct klp_patch *patch, int enable, * the stack. */ if (list_is_singular(&func_node->func_stack)) { - func_addr = (unsigned long)func->old_func; + func_addr = old_func; func_size = func->old_size; } else { struct klp_func *prev; @@ -219,6 +229,13 @@ static int klp_check_activeness_func(struct klp_patch *patch, int enable, func->old_name, 0); if (ret) return ret; + if (func_addr != old_func) { + ret = add_func_to_list(check_funcs, &pcheck, + old_func, func->old_size, + func->old_name, 0); + if (ret) + return ret; + } #endif func_addr = (unsigned long)func->new_func; func_size = func->new_size; diff --git a/arch/arm64/kernel/livepatch.c b/arch/arm64/kernel/livepatch.c index 6b5bcb491125..d1a1dd4fb87a 100644 --- a/arch/arm64/kernel/livepatch.c +++ b/arch/arm64/kernel/livepatch.c @@ -126,12 +126,15 @@ static int klp_check_activeness_func(struct klp_patch *patch, int enable, int ret; struct klp_object *obj; struct klp_func *func; - unsigned long func_addr, func_size; + unsigned long func_addr = 0; + unsigned long func_size; struct klp_func_node *func_node; struct klp_func_list *pcheck = NULL; for (obj = patch->objs; obj->funcs; obj++) { for (func = obj->funcs; func->old_name; func++) { + unsigned long old_func = (unsigned long)func->old_func; + if (enable) { if (func->patched || func->force == KLP_ENFORCEMENT) continue; @@ -142,7 +145,7 @@ static int klp_check_activeness_func(struct klp_patch *patch, int enable, func_node = klp_find_func_node(func->old_func); if (!func_node || list_empty(&func_node->func_stack)) { - func_addr = (unsigned long)func->old_func; + func_addr = old_func; func_size = func->old_size; } else { /* @@ -173,6 +176,13 @@ static int klp_check_activeness_func(struct klp_patch *patch, int enable, func->old_name, func->force); if (ret) return ret; + if (func_addr != old_func) { + ret = add_func_to_list(check_funcs, &pcheck, + old_func, func->old_size, + func->old_name, func->force); + if (ret) + return ret; + } } } else { /* @@ -193,7 +203,7 @@ static int klp_check_activeness_func(struct klp_patch *patch, int enable, * the stack. */ if (list_is_singular(&func_node->func_stack)) { - func_addr = (unsigned long)func->old_func; + func_addr = old_func; func_size = func->old_size; } else { struct klp_func *prev; @@ -209,6 +219,13 @@ static int klp_check_activeness_func(struct klp_patch *patch, int enable, func->old_name, 0); if (ret) return ret; + if (func_addr != old_func) { + ret = add_func_to_list(check_funcs, &pcheck, + old_func, func->old_size, + func->old_name, 0); + if (ret) + return ret; + } #endif func_addr = (unsigned long)func->new_func; diff --git a/arch/powerpc/kernel/livepatch_32.c b/arch/powerpc/kernel/livepatch_32.c index 7b4ed23bf2ca..d5bbc58739e1 100644 --- a/arch/powerpc/kernel/livepatch_32.c +++ b/arch/powerpc/kernel/livepatch_32.c @@ -123,12 +123,15 @@ static int klp_check_activeness_func(struct klp_patch *patch, int enable, int ret; struct klp_object *obj; struct klp_func *func; - unsigned long func_addr, func_size; + unsigned long func_addr = 0; + unsigned long func_size; struct klp_func_node *func_node; struct klp_func_list *pcheck = NULL; for (obj = patch->objs; obj->funcs; obj++) { for (func = obj->funcs; func->old_name; func++) { + unsigned long old_func = (unsigned long)func->old_func; + if (enable) { if (func->patched || func->force == KLP_ENFORCEMENT) continue; @@ -143,7 +146,7 @@ static int klp_check_activeness_func(struct klp_patch *patch, int enable, * No patched on this function * [ the origin one ] */ - func_addr = (unsigned long)func->old_func; + func_addr = old_func; func_size = func->old_size; } else { /* @@ -174,6 +177,13 @@ static int klp_check_activeness_func(struct klp_patch *patch, int enable, func->old_name, func->force); if (ret) return ret; + if (func_addr != old_func) { + ret = add_func_to_list(check_funcs, &pcheck, + old_func, func->old_size, + func->old_name, func->force); + if (ret) + return ret; + } } } else { /* @@ -193,7 +203,7 @@ static int klp_check_activeness_func(struct klp_patch *patch, int enable, * the stack. */ if (list_is_singular(&func_node->func_stack)) { - func_addr = (unsigned long)func->old_func; + func_addr = old_func; func_size = func->old_size; } else { struct klp_func *prev; @@ -208,6 +218,12 @@ static int klp_check_activeness_func(struct klp_patch *patch, int enable, func_size, func->old_name, 0); if (ret) return ret; + if (func_addr != old_func) { + ret = add_func_to_list(check_funcs, &pcheck, old_func, + func->old_size, func->old_name, 0); + if (ret) + return ret; + } #endif func_addr = (unsigned long)func->new_func; func_size = func->new_size; diff --git a/arch/x86/kernel/livepatch.c b/arch/x86/kernel/livepatch.c index 0241e560bd2e..d6e10df5e622 100644 --- a/arch/x86/kernel/livepatch.c +++ b/arch/x86/kernel/livepatch.c @@ -120,14 +120,16 @@ static int klp_check_activeness_func(struct klp_patch *patch, int enable, int ret; struct klp_object *obj; struct klp_func *func; - unsigned long func_addr, func_size; + unsigned long func_addr = 0; + unsigned long func_size; struct klp_func_node *func_node = NULL; struct klp_func_list *pcheck = NULL; for (obj = patch->objs; obj->funcs; obj++) { for (func = obj->funcs; func->old_name; func++) { - func_node = klp_find_func_node(func->old_func); + unsigned long old_func = (unsigned long)func->old_func; + func_node = klp_find_func_node(func->old_func); /* Check func address in stack */ if (enable) { if (func->patched || func->force == KLP_ENFORCEMENT) @@ -138,7 +140,7 @@ static int klp_check_activeness_func(struct klp_patch *patch, int enable, */ if (!func_node || list_empty(&func_node->func_stack)) { - func_addr = (unsigned long)func->old_func; + func_addr = old_func; func_size = func->old_size; } else { /* @@ -169,6 +171,13 @@ static int klp_check_activeness_func(struct klp_patch *patch, int enable, func->old_name, func->force); if (ret) return ret; + if (func_addr != old_func) { + ret = add_func_to_list(check_funcs, &pcheck, + old_func, func->old_size, + func->old_name, func->force); + if (ret) + return ret; + } } } else { /* @@ -186,7 +195,7 @@ static int klp_check_activeness_func(struct klp_patch *patch, int enable, * the stack. */ if (list_is_singular(&func_node->func_stack)) { - func_addr = (unsigned long)func->old_func; + func_addr = old_func; func_size = func->old_size; } else { struct klp_func *prev; @@ -201,6 +210,12 @@ static int klp_check_activeness_func(struct klp_patch *patch, int enable, func_size, func->old_name, 0); if (ret) return ret; + if (func_addr != old_func) { + ret = add_func_to_list(check_funcs, &pcheck, old_func, + func->old_size, func->old_name, 0); + if (ret) + return ret; + } #endif func_addr = (unsigned long)func->new_func; -- 2.25.1

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[PATCH openEuler-1.0-LTS] livepatch/core: Fix possible issue that old function is not checked
by Zheng Yejian 07 Sep '23

07 Sep '23

hulk inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I7ZH67 CVE: NA -------------------------------- After patch being enabled, the first few instructions would be modified to jump to the new function, then callers of old function would jump to new function but always through the old function. Therefore when enabling a new patch or disable a patch on the old function, we should always consider that old function is running. Otherwise, there may be situations where old functions are being modified before jumping to new function and cause issues. Signed-off-by: Zheng Yejian <zhengyejian1(a)huawei.com> --- arch/arm64/kernel/livepatch.c | 6 ++++++ arch/x86/kernel/livepatch.c | 3 +++ 2 files changed, 9 insertions(+) diff --git a/arch/arm64/kernel/livepatch.c b/arch/arm64/kernel/livepatch.c index 235e6f8b6719..4bb27fc703fb 100644 --- a/arch/arm64/kernel/livepatch.c +++ b/arch/arm64/kernel/livepatch.c @@ -144,6 +144,12 @@ static int klp_check_activeness_func(struct stackframe *frame, void *data) func_size, func_name); if (args->ret) return args->ret; + if (func_addr != func->old_addr) { + args->ret = klp_compare_address(frame->pc, func->old_addr, + func->old_size, func_name); + if (args->ret) + return args->ret; + } } } diff --git a/arch/x86/kernel/livepatch.c b/arch/x86/kernel/livepatch.c index 785bba03b77f..7bc8325790a1 100644 --- a/arch/x86/kernel/livepatch.c +++ b/arch/x86/kernel/livepatch.c @@ -166,6 +166,9 @@ static int klp_check_stack_func(struct klp_func *func, if (klp_compare_address(address, func_addr, func_size, func_name)) return -EAGAIN; + if (func_addr != func->old_addr && + klp_compare_address(address, func->old_addr, func->old_size, func_name)) + return -EAGAIN; } return 0; -- 2.25.1

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[PATCH openEuler-1.0-LTS 0/8] x86/speculation: Add Gather Data Sampling mitigation
by Zeng Heng 07 Sep '23

07 Sep '23

Arnd Bergmann (2): x86/speculation: Add cpu_show_gds() prototype x86: Move gds_ucode_mitigated() declaration to header Daniel Sneddon (4): x86/speculation: Add Gather Data Sampling mitigation x86/speculation: Add force option to GDS mitigation x86/speculation: Add Kconfig option for GDS KVM: Add GDS_NO support to KVM Dave Hansen (2): Documentation/x86: Fix backwards on/off logic about YMM support x86/speculation: Mark all Skylake CPUs as vulnerable to GDS .../ABI/testing/sysfs-devices-system-cpu | 11 +- .../hw-vuln/gather_data_sampling.rst | 109 ++++++++++++ Documentation/admin-guide/hw-vuln/index.rst | 1 + .../admin-guide/kernel-parameters.txt | 39 ++++- arch/x86/Kconfig | 19 +++ arch/x86/include/asm/cpufeatures.h | 3 +- arch/x86/include/asm/msr-index.h | 11 ++ arch/x86/include/asm/processor.h | 2 + arch/x86/kernel/cpu/bugs.c | 158 ++++++++++++++++++ arch/x86/kernel/cpu/common.c | 40 +++-- arch/x86/kernel/cpu/cpu.h | 1 + arch/x86/kvm/x86.c | 3 + drivers/base/cpu.c | 8 + include/linux/cpu.h | 8 +- 14 files changed, 383 insertions(+), 30 deletions(-) create mode 100644 Documentation/admin-guide/hw-vuln/gather_data_sampling.rst -- 2.25.1

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[PATCH openEuler-1.0-LTS] memcg: add refcnt for pcpu stock to avoid UAF problem in drain_all_stock()
by GONG, Ruiqi 07 Sep '23

07 Sep '23

hulk inclusion category: bugfix bugzilla: 189183, https://gitee.com/openeuler/kernel/issues/I7Z1ZU CVE: NA ---------------------------------------- It is found that the last bugfix patch for this problem is not enough for higher version like 4.19, since drain_all_stock() now has nothing to do with css's offline process, and so a memcg could still be on the stock after it's been freed. Fix this problem by adding (and decreasing) css's refcnt when the css is put onto (and removed from) stock. After all, "being on the stock" is a kind of reference with regards to memcg. As such, it's guaranteed that a css on stock would not be freed. Signed-off-by: GONG, Ruiqi <gongruiqi1(a)huawei.com> --- mm/memcontrol.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 032bb52cd2ed..29d430885b1a 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2149,6 +2149,9 @@ static void drain_stock(struct memcg_stock_pcp *stock) { struct mem_cgroup *old = stock->cached; + if (!old) + return; + if (stock->nr_pages) { page_counter_uncharge(&old->memory, stock->nr_pages); if (do_memsw_account()) @@ -2156,6 +2159,8 @@ static void drain_stock(struct memcg_stock_pcp *stock) css_put_many(&old->css, stock->nr_pages); stock->nr_pages = 0; } + + css_put(&old->css); stock->cached = NULL; } @@ -2191,6 +2196,7 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages) stock = this_cpu_ptr(&memcg_stock); if (stock->cached != memcg) { /* reset if necessary */ drain_stock(stock); + css_get(&memcg->css); stock->cached = memcg; } stock->nr_pages += nr_pages; -- 2.25.1

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openEuler Kernel SIG 双周例会
by openEuler conference 07 Sep '23

07 Sep '23

您好！ Kernel SIG 邀请您参加 2023-09-08 14:00 召开的Zoom会议(自动录制) 会议主题：openEuler Kernel SIG 双周例会会议内容： 1. 进展update 2. 议题征集中（新增议题可以回复会议邮件，也可直接填至会议看板）会议链接：https://us06web.zoom.us/j/82146435494?pwd=ek56cW1UYmljbXZXRTlhWVNnRVpLUT09 会议纪要：https://etherpad.openeuler.org/p/Kernel-meetings 温馨提醒：建议接入会议后修改参会人的姓名，也可以使用您在gitee.com的ID 更多资讯尽在：https://openeuler.org/zh/ Hello! openEuler Kernel SIG invites you to attend the Zoom conference(auto recording) will be held at 2023-09-08 14:00, The subject of the conference is openEuler Kernel SIG 双周例会, Summary: 1. 进展update 2. 议题征集中（新增议题可以回复会议邮件，也可直接填至会议看板） You can join the meeting at https://us06web.zoom.us/j/82146435494?pwd=ek56cW1UYmljbXZXRTlhWVNnRVpLUT09. Add topics at https://etherpad.openeuler.org/p/Kernel-meetings. Note: You are advised to change the participant name after joining the conference or use your ID at gitee.com. More information: https://openeuler.org/en/

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[PATCH openEuler-1.0-LTS 0/8] x86/speculation: Add Gather Data Sampling mitigation
by Zeng Heng 07 Sep '23

07 Sep '23

Arnd Bergmann (2): x86/speculation: Add cpu_show_gds() prototype x86: Move gds_ucode_mitigated() declaration to header Daniel Sneddon (4): x86/speculation: Add Gather Data Sampling mitigation x86/speculation: Add force option to GDS mitigation x86/speculation: Add Kconfig option for GDS KVM: Add GDS_NO support to KVM Dave Hansen (2): x86/speculation: Mark all Skylake CPUs as vulnerable to GDS Documentation/x86: Fix backwards on/off logic about YMM support .../ABI/testing/sysfs-devices-system-cpu | 11 +- .../hw-vuln/gather_data_sampling.rst | 109 ++++++++++++ Documentation/admin-guide/hw-vuln/index.rst | 1 + .../admin-guide/kernel-parameters.txt | 39 ++++- arch/x86/Kconfig | 19 +++ arch/x86/include/asm/cpufeatures.h | 3 +- arch/x86/include/asm/msr-index.h | 11 ++ arch/x86/include/asm/processor.h | 2 + arch/x86/kernel/cpu/bugs.c | 158 ++++++++++++++++++ arch/x86/kernel/cpu/common.c | 40 +++-- arch/x86/kernel/cpu/cpu.h | 1 + arch/x86/kvm/x86.c | 3 + drivers/base/cpu.c | 8 + include/linux/cpu.h | 8 +- 14 files changed, 385 insertions(+), 28 deletions(-) create mode 100644 Documentation/admin-guide/hw-vuln/gather_data_sampling.rst -- 2.25.1

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[PATCH OLK-5.10] dm: switch to precise io accounting
by Li Nan 07 Sep '23

07 Sep '23

hulk inclusion category: bugfix bugzilla: 188421, https://gitee.com/openeuler/kernel/issues/I7WMMI CVE: NA -------------------------------- 'ios' and 'sectors' is counted in bio_start_io_acct() while io is started insted of io is done. Hence switch to precise io accounting to count them when io is done. Signed-off-by: Li Nan <linan122(a)huawei.com> --- drivers/md/dm.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 06318a0efc67..c925ff1bf900 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -587,7 +587,7 @@ static void start_io_acct(struct dm_io *io) struct mapped_device *md = io->md; struct bio *bio = io->orig_bio; - io->start_time = bio_start_io_acct(bio); + io->start_time = bio_start_precise_io_acct(bio); if (unlikely(dm_stats_used(&md->stats))) dm_stats_account_io(&md->stats, bio_data_dir(bio), bio->bi_iter.bi_sector, bio_sectors(bio), @@ -606,7 +606,7 @@ static void end_io_acct(struct mapped_device *md, struct bio *bio, smp_wmb(); - bio_end_io_acct(bio, start_time); + bio_end_precise_io_acct(bio, start_time); /* nudge anyone waiting on suspend queue */ if (unlikely(wq_has_sleeper(&md->wait))) -- 2.39.2

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[openEuler-1.0-LTS 0/3] scsi: scsi_device_gets returns failure when the module is NULL.
by Zhong Jinghua 07 Sep '23

07 Sep '23

Fix scsi mod UAF problem. Li Lingfeng (2): scsi: don't fail if hostt->module is NULL scsi: fix kabi broken in struct Scsi_Host Zhong Jinghua (1): scsi: scsi_device_gets returns failure when the module is NULL. drivers/scsi/hosts.c | 3 +++ drivers/scsi/scsi.c | 6 +++++- include/scsi/scsi_host.h | 2 +- 3 files changed, 9 insertions(+), 2 deletions(-) -- 2.31.1

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[PATCH openEuler-1.0-LTS 0/7] x86/speculation: Add Gather Data Sampling mitigation
by Zeng Heng 07 Sep '23

07 Sep '23

Arnd Bergmann (2): x86/speculation: Add cpu_show_gds() prototype x86: Move gds_ucode_mitigated() declaration to header Daniel Sneddon (4): x86/speculation: Add Gather Data Sampling mitigation x86/speculation: Add force option to GDS mitigation x86/speculation: Add Kconfig option for GDS KVM: Add GDS_NO support to KVM Dave Hansen (1): Documentation/x86: Fix backwards on/off logic about YMM support .../ABI/testing/sysfs-devices-system-cpu | 11 +- .../hw-vuln/gather_data_sampling.rst | 109 ++++++++++++ Documentation/admin-guide/hw-vuln/index.rst | 1 + .../admin-guide/kernel-parameters.txt | 39 ++++- arch/x86/Kconfig | 19 +++ arch/x86/include/asm/cpufeatures.h | 3 +- arch/x86/include/asm/msr-index.h | 11 ++ arch/x86/include/asm/processor.h | 2 + arch/x86/kernel/cpu/bugs.c | 158 ++++++++++++++++++ arch/x86/kernel/cpu/common.c | 36 ++-- arch/x86/kernel/cpu/cpu.h | 1 + arch/x86/kvm/x86.c | 3 + drivers/base/cpu.c | 8 + include/linux/cpu.h | 8 +- 14 files changed, 381 insertions(+), 28 deletions(-) create mode 100644 Documentation/admin-guide/hw-vuln/gather_data_sampling.rst -- 2.25.1

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[PATCH openEuler-1.0-LTS] cpu/hotplug: Prevent self deadlock on CPU hot-unplug
by Yu Liao 07 Sep '23

07 Sep '23

From: Thomas Gleixner <tglx(a)linutronix.de> mainline inclusion from mainline-v6.6-rc1 commit 2b8272ff4a70b866106ae13c36be7ecbef5d5da2 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I7Y6AQ Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?… -------------------------------- Xiongfeng reported and debugged a self deadlock of the task which initiates and controls a CPU hot-unplug operation vs. the CFS bandwidth timer. CPU1 CPU2 T1 sets cfs_quota starts hrtimer cfs_bandwidth 'period_timer' T1 is migrated to CPU2 T1 initiates offlining of CPU1 Hotplug operation starts ... 'period_timer' expires and is re-enqueued on CPU1 ... take_cpu_down() CPU1 shuts down and does not handle timers anymore. They have to be migrated in the post dead hotplug steps by the control task. T1 runs the post dead offline operation T1 is scheduled out T1 waits for 'period_timer' to expire T1 waits there forever if it is scheduled out before it can execute the hrtimer offline callback hrtimers_dead_cpu(). Cure this by delegating the hotplug control operation to a worker thread on an online CPU. This takes the initiating user space task, which might be affected by the bandwidth timer, completely out of the picture. Reported-by: Xiongfeng Wang <wangxiongfeng2(a)huawei.com> Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de> Tested-by: Yu Liao <liaoyu15(a)huawei.com> Acked-by: Vincent Guittot <vincent.guittot(a)linaro.org> Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/lkml/8e785777-03aa-99e1-d20e-e956f5685be6@huawei.com Link: https://lore.kernel.org/r/87h6oqdq0i.ffs@tglx Conflict: kernel/cpu.c Signed-off-by: Yu Liao <liaoyu15(a)huawei.com> --- kernel/cpu.c | 24 +++++++++++++++++++++++- 1 file changed, 23 insertions(+), 1 deletion(-) diff --git a/kernel/cpu.c b/kernel/cpu.c index b3b04e7c17d8..c943454b748e 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -1018,11 +1018,33 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen, return ret; } +struct cpu_down_work { + unsigned int cpu; + enum cpuhp_state target; +}; + +static long __cpu_down_maps_locked(void *arg) +{ + struct cpu_down_work *work = arg; + + return _cpu_down(work->cpu, 0, work->target); +} + static int cpu_down_maps_locked(unsigned int cpu, enum cpuhp_state target) { + struct cpu_down_work work = { .cpu = cpu, .target = target, }; + if (cpu_hotplug_disabled) return -EBUSY; - return _cpu_down(cpu, 0, target); + + /* + * Ensure that the control task does not run on the to be offlined + * CPU to prevent a deadlock against cfs_b->period_timer. + */ + cpu = cpumask_any_but(cpu_online_mask, cpu); + if (cpu >= nr_cpu_ids) + return -EBUSY; + return work_on_cpu(cpu, __cpu_down_maps_locked, &work); } static int do_cpu_down(unsigned int cpu, enum cpuhp_state target) -- 2.25.1

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