April 2025 - Linux-stable-mirror

+ mm-protect-kernel-pgtables-in-apply_to_pte_range.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: mm: protect kernel pgtables in apply_to_pte_range() has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-protect-kernel-pgtables-in-apply_to_pte_range.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Alexander Gordeev <agordeev(a)linux.ibm.com> Subject: mm: protect kernel pgtables in apply_to_pte_range() Date: Tue, 8 Apr 2025 18:07:32 +0200 The lazy MMU mode can only be entered and left under the protection of the page table locks for all page tables which may be modified. Yet, when it comes to kernel mappings apply_to_pte_range() does not take any locks. That does not conform arch_enter|leave_lazy_mmu_mode() semantics and could potentially lead to re-schedulling a process while in lazy MMU mode or racing on a kernel page table updates. Link: https://lkml.kernel.org/r/ef8f6538b83b7fc3372602f90375348f9b4f3596.17441281… Fixes: 38e0edb15bd0 ("mm/apply_to_range: call pte function with lazy updates") Signed-off-by: Alexander Gordeev <agordeev(a)linux.ibm.com> Cc: <stable(a)vger.kernel.org> Cc: Andrey Ryabinin <ryabinin.a.a(a)gmail.com> Cc: Guenetr Roeck <linux(a)roeck-us.net> Cc: Hugh Dickins <hughd(a)google.com> Cc: Jeremy Fitzhardinge <jeremy(a)goop.org> Cc: Juegren Gross <jgross(a)suse.com> Cc: Nicholas Piggin <npiggin(a)gmail.com> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/kasan/shadow.c | 7 ++----- mm/memory.c | 5 ++++- 2 files changed, 6 insertions(+), 6 deletions(-) --- a/mm/kasan/shadow.c~mm-protect-kernel-pgtables-in-apply_to_pte_range +++ a/mm/kasan/shadow.c @@ -308,14 +308,14 @@ static int kasan_populate_vmalloc_pte(pt __memset((void *)page, KASAN_VMALLOC_INVALID, PAGE_SIZE); pte = pfn_pte(PFN_DOWN(__pa(page)), PAGE_KERNEL); - spin_lock(&init_mm.page_table_lock); if (likely(pte_none(ptep_get(ptep)))) { set_pte_at(&init_mm, addr, ptep, pte); page = 0; } - spin_unlock(&init_mm.page_table_lock); + if (page) free_page(page); + return 0; } @@ -401,13 +401,10 @@ static int kasan_depopulate_vmalloc_pte( page = (unsigned long)__va(pte_pfn(ptep_get(ptep)) << PAGE_SHIFT); - spin_lock(&init_mm.page_table_lock); - if (likely(!pte_none(ptep_get(ptep)))) { pte_clear(&init_mm, addr, ptep); free_page(page); } - spin_unlock(&init_mm.page_table_lock); return 0; } --- a/mm/memory.c~mm-protect-kernel-pgtables-in-apply_to_pte_range +++ a/mm/memory.c @@ -2926,6 +2926,7 @@ static int apply_to_pte_range(struct mm_ pte = pte_offset_kernel(pmd, addr); if (!pte) return err; + spin_lock(&init_mm.page_table_lock); } else { if (create) pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); @@ -2951,7 +2952,9 @@ static int apply_to_pte_range(struct mm_ arch_leave_lazy_mmu_mode(); - if (mm != &init_mm) + if (mm == &init_mm) + spin_unlock(&init_mm.page_table_lock); + else pte_unmap_unlock(mapped_pte, ptl); *mask |= PGTBL_PTE_MODIFIED; _ Patches currently in -mm which might be from agordeev(a)linux.ibm.com are kasan-avoid-sleepable-page-allocation-from-atomic-context.patch mm-cleanup-apply_to_pte_range-routine.patch mm-protect-kernel-pgtables-in-apply_to_pte_range.patch

4 months, 2 weeks

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+ mm-cleanup-apply_to_pte_range-routine.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: mm: clean up apply_to_pte_range() has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-cleanup-apply_to_pte_range-routine.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Alexander Gordeev <agordeev(a)linux.ibm.com> Subject: mm: clean up apply_to_pte_range() Date: Tue, 8 Apr 2025 18:07:31 +0200 Reverse 'create' vs 'mm == &init_mm' conditions and move page table mask modification out of the atomic context. This is a prerequisite for fixing missing kernel page tables lock. Link: https://lkml.kernel.org/r/0c65bc334f17ff1d7d92d31c69d7065769bbce4e.17441281… Fixes: 38e0edb15bd0 ("mm/apply_to_range: call pte function with lazy updates") Signed-off-by: Alexander Gordeev <agordeev(a)linux.ibm.com> Cc: <stable(a)vger.kernel.org> Cc: Andrey Ryabinin <ryabinin.a.a(a)gmail.com> Cc: Guenetr Roeck <linux(a)roeck-us.net> Cc: Hugh Dickins <hughd(a)google.com> Cc: Jeremy Fitzhardinge <jeremy(a)goop.org> Cc: Juegren Gross <jgross(a)suse.com> Cc: Nicholas Piggin <npiggin(a)gmail.com> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/memory.c | 28 +++++++++++++++++----------- 1 file changed, 17 insertions(+), 11 deletions(-) --- a/mm/memory.c~mm-cleanup-apply_to_pte_range-routine +++ a/mm/memory.c @@ -2915,24 +2915,28 @@ static int apply_to_pte_range(struct mm_ pte_fn_t fn, void *data, bool create, pgtbl_mod_mask *mask) { + int err = create ? -ENOMEM : -EINVAL; pte_t *pte, *mapped_pte; - int err = 0; spinlock_t *ptl; - if (create) { - mapped_pte = pte = (mm == &init_mm) ? - pte_alloc_kernel_track(pmd, addr, mask) : - pte_alloc_map_lock(mm, pmd, addr, &ptl); + if (mm == &init_mm) { + if (create) + pte = pte_alloc_kernel_track(pmd, addr, mask); + else + pte = pte_offset_kernel(pmd, addr); if (!pte) - return -ENOMEM; + return err; } else { - mapped_pte = pte = (mm == &init_mm) ? - pte_offset_kernel(pmd, addr) : - pte_offset_map_lock(mm, pmd, addr, &ptl); + if (create) + pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); + else + pte = pte_offset_map_lock(mm, pmd, addr, &ptl); if (!pte) - return -EINVAL; + return err; + mapped_pte = pte; } + err = 0; arch_enter_lazy_mmu_mode(); if (fn) { @@ -2944,12 +2948,14 @@ static int apply_to_pte_range(struct mm_ } } while (addr += PAGE_SIZE, addr != end); } - *mask |= PGTBL_PTE_MODIFIED; arch_leave_lazy_mmu_mode(); if (mm != &init_mm) pte_unmap_unlock(mapped_pte, ptl); + + *mask |= PGTBL_PTE_MODIFIED; + return err; } _ Patches currently in -mm which might be from agordeev(a)linux.ibm.com are kasan-avoid-sleepable-page-allocation-from-atomic-context.patch mm-cleanup-apply_to_pte_range-routine.patch mm-protect-kernel-pgtables-in-apply_to_pte_range.patch

4 months, 2 weeks

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+ kasan-avoid-sleepable-page-allocation-from-atomic-context.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: kasan: avoid sleepable page allocation from atomic context has been added to the -mm mm-hotfixes-unstable branch. Its filename is kasan-avoid-sleepable-page-allocation-from-atomic-context.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Alexander Gordeev <agordeev(a)linux.ibm.com> Subject: kasan: avoid sleepable page allocation from atomic context Date: Tue, 8 Apr 2025 18:07:30 +0200 Patch series "mm: Fix apply_to_pte_range() vs lazy MMU mode", v2. This series is an attempt to fix the violation of lazy MMU mode context requirement as described for arch_enter_lazy_mmu_mode(): This mode can only be entered and left under the protection of the page table locks for all page tables which may be modified. On s390 if I make arch_enter_lazy_mmu_mode() -> preempt_enable() and arch_leave_lazy_mmu_mode() -> preempt_disable() I am getting this: [ 553.332108] preempt_count: 1, expected: 0 [ 553.332117] no locks held by multipathd/2116. [ 553.332128] CPU: 24 PID: 2116 Comm: multipathd Kdump: loaded Tainted: [ 553.332139] Hardware name: IBM 3931 A01 701 (LPAR) [ 553.332146] Call Trace: [ 553.332152] [<00000000158de23a>] dump_stack_lvl+0xfa/0x150 [ 553.332167] [<0000000013e10d12>] __might_resched+0x57a/0x5e8 [ 553.332178] [<00000000144eb6c2>] __alloc_pages+0x2ba/0x7c0 [ 553.332189] [<00000000144d5cdc>] __get_free_pages+0x2c/0x88 [ 553.332198] [<00000000145663f6>] kasan_populate_vmalloc_pte+0x4e/0x110 [ 553.332207] [<000000001447625c>] apply_to_pte_range+0x164/0x3c8 [ 553.332218] [<000000001448125a>] apply_to_pmd_range+0xda/0x318 [ 553.332226] [<000000001448181c>] __apply_to_page_range+0x384/0x768 [ 553.332233] [<0000000014481c28>] apply_to_page_range+0x28/0x38 [ 553.332241] [<00000000145665da>] kasan_populate_vmalloc+0x82/0x98 [ 553.332249] [<00000000144c88d0>] alloc_vmap_area+0x590/0x1c90 [ 553.332257] [<00000000144ca108>] __get_vm_area_node.constprop.0+0x138/0x260 [ 553.332265] [<00000000144d17fc>] __vmalloc_node_range+0x134/0x360 [ 553.332274] [<0000000013d5dbf2>] alloc_thread_stack_node+0x112/0x378 [ 553.332284] [<0000000013d62726>] dup_task_struct+0x66/0x430 [ 553.332293] [<0000000013d63962>] copy_process+0x432/0x4b80 [ 553.332302] [<0000000013d68300>] kernel_clone+0xf0/0x7d0 [ 553.332311] [<0000000013d68bd6>] __do_sys_clone+0xae/0xc8 [ 553.332400] [<0000000013d68dee>] __s390x_sys_clone+0xd6/0x118 [ 553.332410] [<0000000013c9d34c>] do_syscall+0x22c/0x328 [ 553.332419] [<00000000158e7366>] __do_syscall+0xce/0xf0 [ 553.332428] [<0000000015913260>] system_call+0x70/0x98 This exposes a KASAN issue fixed with patch 1 and apply_to_pte_range() issue fixed with patch 3, while patch 2 is a prerequisite. Commit b9ef323ea168 ("powerpc/64s: Disable preemption in hash lazy mmu mode") looks like powerpc-only fix, yet not entirely conforming to the above provided requirement (page tables itself are still not protected). If I am not mistaken, xen and sparc are alike. This patch (of 3): apply_to_page_range() enters lazy MMU mode and then invokes kasan_populate_vmalloc_pte() callback on each page table walk iteration. The lazy MMU mode may only be entered only under protection of the page table lock. However, the callback can go into sleep when trying to allocate a single page. Change __get_free_page() allocation mode from GFP_KERNEL to GFP_ATOMIC to avoid scheduling out while in atomic context. Link: https://lkml.kernel.org/r/cover.1744128123.git.agordeev@linux.ibm.com Link: https://lkml.kernel.org/r/2d9f4ac4528701b59d511a379a60107fa608ad30.17441281… Fixes: 3c5c3cfb9ef4 ("kasan: support backing vmalloc space with real shadow memory") Signed-off-by: Alexander Gordeev <agordeev(a)linux.ibm.com> Cc: Andrey Ryabinin <ryabinin.a.a(a)gmail.com> Cc: Guenetr Roeck <linux(a)roeck-us.net> Cc: Hugh Dickins <hughd(a)google.com> Cc: Jeremy Fitzhardinge <jeremy(a)goop.org> Cc: Juegren Gross <jgross(a)suse.com> Cc: Nicholas Piggin <npiggin(a)gmail.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/kasan/shadow.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/kasan/shadow.c~kasan-avoid-sleepable-page-allocation-from-atomic-context +++ a/mm/kasan/shadow.c @@ -301,7 +301,7 @@ static int kasan_populate_vmalloc_pte(pt if (likely(!pte_none(ptep_get(ptep)))) return 0; - page = __get_free_page(GFP_KERNEL); + page = __get_free_page(GFP_ATOMIC); if (!page) return -ENOMEM; _ Patches currently in -mm which might be from agordeev(a)linux.ibm.com are kasan-avoid-sleepable-page-allocation-from-atomic-context.patch mm-cleanup-apply_to_pte_range-routine.patch mm-protect-kernel-pgtables-in-apply_to_pte_range.patch

4 months, 2 weeks

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[PATCH v6 0/4] samsung: pinctrl: Add support for eint_fltcon_offset and filter selection on gs101

by Peter Griffin

Hi folks, This series fixes support for correctly saving and restoring fltcon0 and fltcon1 registers on gs101 for non-alive banks where the fltcon register offset is not at a fixed offset (unlike previous SoCs). This is done by adding a eint_fltcon_offset and providing GS101 specific pin macros that take an additional parameter (similar to how exynosautov920 handles it's eint_con_offset). Additionally the SoC specific suspend and resume callbacks are re-factored so that each SoC variant has it's own callback containing the peculiarities for that SoC. Finally support for filter selection on alive banks is added, this is currently only enabled for gs101. The code path can be excercised using `echo mem > /sys/power/state` regards, Peter To: Krzysztof Kozlowski <krzk(a)kernel.org> To: Sylwester Nawrocki <s.nawrocki(a)samsung.com> To: Alim Akhtar <alim.akhtar(a)samsung.com> To: Linus Walleij <linus.walleij(a)linaro.org> Cc: linux-arm-kernel(a)lists.infradead.org Cc: linux-samsung-soc(a)vger.kernel.org Cc: linux-gpio(a)vger.kernel.org Cc: linux-kernel(a)vger.kernel.org Cc: andre.draszik(a)linaro.org Cc: tudor.ambarus(a)linaro.org Cc: willmcvicker(a)google.com Cc: semen.protsenko(a)linaro.org Cc: kernel-team(a)android.com Cc: jaewon02.kim(a)samsung.com Signed-off-by: Peter Griffin <peter.griffin(a)linaro.org> --- Changes in v6: - Make drvdata->suspend/resume symmetrically reversed (Krzysztof) - rebase on linux-next - Link to v5: https://lore.kernel.org/r/20250312-pinctrl-fltcon-suspend-v5-0-d98d5b271242… Changes in v5: - Split drvdata suspend & resume callbacks into a dedicated patch (Krzysztof) - Add comment about stable dependency (Krzysztof) - Add back in {} braces (Krzysztof) - Link to v4: https://lore.kernel.org/r/20250307-pinctrl-fltcon-suspend-v4-0-2d775e486036… Changes in v4: - save->eint_fltcon1 is an argument to pr_debug(), not readl() change alignment accordingly (Andre) - Link to v3: https://lore.kernel.org/r/20250306-pinctrl-fltcon-suspend-v3-0-f9ab4ff6a24e… Changes in v3: - Ensure EXYNOS_FLTCON_DIGITAL bit is cleared (Andre) - Make it obvious that exynos_eint_set_filter() is conditional on bank type (Andre) - Make it obvious exynos_set_wakeup() is conditional on bank type (Andre) - Align style where the '+' is placed first (Andre) - Remove unnecessary braces (Andre) - Link to v2: https://lore.kernel.org/r/20250301-pinctrl-fltcon-suspend-v2-0-a7eef9bb443b… Changes in v2: - Remove eint_flt_selectable bool as it can be deduced from EINT_TYPE_WKUP (Peter) - Move filter config register comment to header file (Andre) - Rename EXYNOS_FLTCON_DELAY to EXYNOS_FLTCON_ANALOG (Andre) - Remove misleading old comment (Andre) - Refactor exynos_eint_update_flt_reg() into a loop (Andre) - Split refactor of suspend/resume callbacks & gs101 parts into separate patches (Andre) - Link to v1: https://lore.kernel.org/r/20250120-pinctrl-fltcon-suspend-v1-0-e77900b2a854… --- Peter Griffin (4): pinctrl: samsung: refactor drvdata suspend & resume callbacks pinctrl: samsung: add dedicated SoC eint suspend/resume callbacks pinctrl: samsung: add gs101 specific eint suspend/resume callbacks pinctrl: samsung: Add filter selection support for alive bank on gs101 drivers/pinctrl/samsung/pinctrl-exynos-arm64.c | 52 ++--- drivers/pinctrl/samsung/pinctrl-exynos.c | 294 +++++++++++++++---------- drivers/pinctrl/samsung/pinctrl-exynos.h | 28 ++- drivers/pinctrl/samsung/pinctrl-samsung.c | 21 +- drivers/pinctrl/samsung/pinctrl-samsung.h | 8 +- 5 files changed, 252 insertions(+), 151 deletions(-) --- base-commit: cd37a617b4bfb43f84dbbf8058317b487f5203ae change-id: 20250120-pinctrl-fltcon-suspend-2333a137c4d4 Best regards, -- Peter Griffin <peter.griffin(a)linaro.org>

4 months, 2 weeks

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[PATCH v3] sched/rt: Fix race in push_rt_task

by Harshit Agarwal

Overview ======== When a CPU chooses to call push_rt_task and picks a task to push to another CPU's runqueue then it will call find_lock_lowest_rq method which would take a double lock on both CPUs' runqueues. If one of the locks aren't readily available, it may lead to dropping the current runqueue lock and reacquiring both the locks at once. During this window it is possible that the task is already migrated and is running on some other CPU. These cases are already handled. However, if the task is migrated and has already been executed and another CPU is now trying to wake it up (ttwu) such that it is queued again on the runqeue (on_rq is 1) and also if the task was run by the same CPU, then the current checks will pass even though the task was migrated out and is no longer in the pushable tasks list. Crashes ======= This bug resulted in quite a few flavors of crashes triggering kernel panics with various crash signatures such as assert failures, page faults, null pointer dereferences, and queue corruption errors all coming from scheduler itself. Some of the crashes: -> kernel BUG at kernel/sched/rt.c:1616! BUG_ON(idx >= MAX_RT_PRIO) Call Trace: ? __die_body+0x1a/0x60 ? die+0x2a/0x50 ? do_trap+0x85/0x100 ? pick_next_task_rt+0x6e/0x1d0 ? do_error_trap+0x64/0xa0 ? pick_next_task_rt+0x6e/0x1d0 ? exc_invalid_op+0x4c/0x60 ? pick_next_task_rt+0x6e/0x1d0 ? asm_exc_invalid_op+0x12/0x20 ? pick_next_task_rt+0x6e/0x1d0 __schedule+0x5cb/0x790 ? update_ts_time_stats+0x55/0x70 schedule_idle+0x1e/0x40 do_idle+0x15e/0x200 cpu_startup_entry+0x19/0x20 start_secondary+0x117/0x160 secondary_startup_64_no_verify+0xb0/0xbb -> BUG: kernel NULL pointer dereference, address: 00000000000000c0 Call Trace: ? __die_body+0x1a/0x60 ? no_context+0x183/0x350 ? __warn+0x8a/0xe0 ? exc_page_fault+0x3d6/0x520 ? asm_exc_page_fault+0x1e/0x30 ? pick_next_task_rt+0xb5/0x1d0 ? pick_next_task_rt+0x8c/0x1d0 __schedule+0x583/0x7e0 ? update_ts_time_stats+0x55/0x70 schedule_idle+0x1e/0x40 do_idle+0x15e/0x200 cpu_startup_entry+0x19/0x20 start_secondary+0x117/0x160 secondary_startup_64_no_verify+0xb0/0xbb -> BUG: unable to handle page fault for address: ffff9464daea5900 kernel BUG at kernel/sched/rt.c:1861! BUG_ON(rq->cpu != task_cpu(p)) -> kernel BUG at kernel/sched/rt.c:1055! BUG_ON(!rq->nr_running) Call Trace: ? __die_body+0x1a/0x60 ? die+0x2a/0x50 ? do_trap+0x85/0x100 ? dequeue_top_rt_rq+0xa2/0xb0 ? do_error_trap+0x64/0xa0 ? dequeue_top_rt_rq+0xa2/0xb0 ? exc_invalid_op+0x4c/0x60 ? dequeue_top_rt_rq+0xa2/0xb0 ? asm_exc_invalid_op+0x12/0x20 ? dequeue_top_rt_rq+0xa2/0xb0 dequeue_rt_entity+0x1f/0x70 dequeue_task_rt+0x2d/0x70 __schedule+0x1a8/0x7e0 ? blk_finish_plug+0x25/0x40 schedule+0x3c/0xb0 futex_wait_queue_me+0xb6/0x120 futex_wait+0xd9/0x240 do_futex+0x344/0xa90 ? get_mm_exe_file+0x30/0x60 ? audit_exe_compare+0x58/0x70 ? audit_filter_rules.constprop.26+0x65e/0x1220 __x64_sys_futex+0x148/0x1f0 do_syscall_64+0x30/0x80 entry_SYSCALL_64_after_hwframe+0x62/0xc7 -> BUG: unable to handle page fault for address: ffff8cf3608bc2c0 Call Trace: ? __die_body+0x1a/0x60 ? no_context+0x183/0x350 ? spurious_kernel_fault+0x171/0x1c0 ? exc_page_fault+0x3b6/0x520 ? plist_check_list+0x15/0x40 ? plist_check_list+0x2e/0x40 ? asm_exc_page_fault+0x1e/0x30 ? _cond_resched+0x15/0x30 ? futex_wait_queue_me+0xc8/0x120 ? futex_wait+0xd9/0x240 ? try_to_wake_up+0x1b8/0x490 ? futex_wake+0x78/0x160 ? do_futex+0xcd/0xa90 ? plist_check_list+0x15/0x40 ? plist_check_list+0x2e/0x40 ? plist_del+0x6a/0xd0 ? plist_check_list+0x15/0x40 ? plist_check_list+0x2e/0x40 ? dequeue_pushable_task+0x20/0x70 ? __schedule+0x382/0x7e0 ? asm_sysvec_reschedule_ipi+0xa/0x20 ? schedule+0x3c/0xb0 ? exit_to_user_mode_prepare+0x9e/0x150 ? irqentry_exit_to_user_mode+0x5/0x30 ? asm_sysvec_reschedule_ipi+0x12/0x20 Above are some of the common examples of the crashes that were observed due to this issue. Details ======= Let's look at the following scenario to understand this race. 1) CPU A enters push_rt_task a) CPU A has chosen next_task = task p. b) CPU A calls find_lock_lowest_rq(Task p, CPU Z’s rq). c) CPU A identifies CPU X as a destination CPU (X < Z). d) CPU A enters double_lock_balance(CPU Z’s rq, CPU X’s rq). e) Since X is lower than Z, CPU A unlocks CPU Z’s rq. Someone else has locked CPU X’s rq, and thus, CPU A must wait. 2) At CPU Z a) Previous task has completed execution and thus, CPU Z enters schedule, locks its own rq after CPU A releases it. b) CPU Z dequeues previous task and begins executing task p. c) CPU Z unlocks its rq. d) Task p yields the CPU (ex. by doing IO or waiting to acquire a lock) which triggers the schedule function on CPU Z. e) CPU Z enters schedule again, locks its own rq, and dequeues task p. f) As part of dequeue, it sets p.on_rq = 0 and unlocks its rq. 3) At CPU B a) CPU B enters try_to_wake_up with input task p. b) Since CPU Z dequeued task p, p.on_rq = 0, and CPU B updates B.state = WAKING. c) CPU B via select_task_rq determines CPU Y as the target CPU. 4) The race a) CPU A acquires CPU X’s lock and relocks CPU Z. b) CPU A reads task p.cpu = Z and incorrectly concludes task p is still on CPU Z. c) CPU A failed to notice task p had been dequeued from CPU Z while CPU A was waiting for locks in double_lock_balance. If CPU A knew that task p had been dequeued, it would return NULL forcing push_rt_task to give up the task p's migration. d) CPU B updates task p.cpu = Y and calls ttwu_queue. e) CPU B locks Ys rq. CPU B enqueues task p onto Y and sets task p.on_rq = 1. f) CPU B unlocks CPU Y, triggering memory synchronization. g) CPU A reads task p.on_rq = 1, cementing its assumption that task p has not migrated. h) CPU A decides to migrate p to CPU X. This leads to A dequeuing p from Y's queue and various crashes down the line. Solution ======== The solution here is fairly simple. After obtaining the lock (at 4a), the check is enhanced to make sure that the task is still at the head of the pushable tasks list. If not, then it is anyway not suitable for being pushed out. Testing ======= The fix is tested on a cluster of 3 nodes, where the panics due to this are hit every couple of days. A fix similar to this was deployed on such cluster and was stable for more than 30 days. Co-developed-by: Jon Kohler <jon(a)nutanix.com> Signed-off-by: Jon Kohler <jon(a)nutanix.com> Co-developed-by: Gauri Patwardhan <gauri.patwardhan(a)nutanix.com> Signed-off-by: Gauri Patwardhan <gauri.patwardhan(a)nutanix.com> Co-developed-by: Rahul Chunduru <rahul.chunduru(a)nutanix.com> Signed-off-by: Rahul Chunduru <rahul.chunduru(a)nutanix.com> Signed-off-by: Harshit Agarwal <harshit(a)nutanix.com> Tested-by: Will Ton <william.ton(a)nutanix.com> Reviewed-by: Steven Rostedt (Google) <rostedt(a)goodmis.org> Cc: stable(a)vger.kernel.org --- Changes in v2: - As per Steve's suggestion, removed some checks that are done after obtaining the lock that are no longer needed with the addition of new check. - Moved up is_migration_disabled check. - Link to v1: https://lore.kernel.org/lkml/20250211054646.23987-1-harshit@nutanix.com/ Changes in v3: - Updated commit message to add stable maintainers and reviewed-by tag. - Link to v2: https://lore.kernel.org/lkml/20250214170844.201692-1-harshit@nutanix.com/ --- kernel/sched/rt.c | 54 +++++++++++++++++++++++------------------------ 1 file changed, 26 insertions(+), 28 deletions(-) diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 4b8e33c615b1..4762dd3f50c5 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1885,6 +1885,27 @@ static int find_lowest_rq(struct task_struct *task) return -1; } +static struct task_struct *pick_next_pushable_task(struct rq *rq) +{ + struct task_struct *p; + + if (!has_pushable_tasks(rq)) + return NULL; + + p = plist_first_entry(&rq->rt.pushable_tasks, + struct task_struct, pushable_tasks); + + BUG_ON(rq->cpu != task_cpu(p)); + BUG_ON(task_current(rq, p)); + BUG_ON(task_current_donor(rq, p)); + BUG_ON(p->nr_cpus_allowed <= 1); + + BUG_ON(!task_on_rq_queued(p)); + BUG_ON(!rt_task(p)); + + return p; +} + /* Will lock the rq it finds */ static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq) { @@ -1915,18 +1936,16 @@ static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq) /* * We had to unlock the run queue. In * the mean time, task could have - * migrated already or had its affinity changed. - * Also make sure that it wasn't scheduled on its rq. + * migrated already or had its affinity changed, + * therefore check if the task is still at the + * head of the pushable tasks list. * It is possible the task was scheduled, set * "migrate_disabled" and then got preempted, so we must * check the task migration disable flag here too. */ - if (unlikely(task_rq(task) != rq || + if (unlikely(is_migration_disabled(task) || !cpumask_test_cpu(lowest_rq->cpu, &task->cpus_mask) || - task_on_cpu(rq, task) || - !rt_task(task) || - is_migration_disabled(task) || - !task_on_rq_queued(task))) { + task != pick_next_pushable_task(rq))) { double_unlock_balance(rq, lowest_rq); lowest_rq = NULL; @@ -1946,27 +1965,6 @@ static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq) return lowest_rq; } -static struct task_struct *pick_next_pushable_task(struct rq *rq) -{ - struct task_struct *p; - - if (!has_pushable_tasks(rq)) - return NULL; - - p = plist_first_entry(&rq->rt.pushable_tasks, - struct task_struct, pushable_tasks); - - BUG_ON(rq->cpu != task_cpu(p)); - BUG_ON(task_current(rq, p)); - BUG_ON(task_current_donor(rq, p)); - BUG_ON(p->nr_cpus_allowed <= 1); - - BUG_ON(!task_on_rq_queued(p)); - BUG_ON(!rt_task(p)); - - return p; -} - /* * If the current CPU has more than one RT task, see if the non * running task can migrate over to a CPU that is running a task -- 2.22.3

4 months, 2 weeks

6
11
0 0

[PATCH v3] sched_ext: Use kvzalloc for large exit_dump allocation

by Breno Leitao

Replace kzalloc with kvzalloc for the exit_dump buffer allocation, which can require large contiguous memory depending on the implementation. This change prevents allocation failures by allowing the system to fall back to vmalloc when contiguous memory allocation fails. Since this buffer is only used for debugging purposes, physical memory contiguity is not required, making vmalloc a suitable alternative. Cc: stable(a)vger.kernel.org Fixes: 07814a9439a3b0 ("sched_ext: Print debug dump after an error exit") Suggested-by: Rik van Riel <riel(a)surriel.com> Signed-off-by: Breno Leitao <leitao(a)debian.org> Acked-by: Andrea Righi <arighi(a)nvidia.com> --- Changes in v3: - Rewording the patch message - Link to v2: https://lore.kernel.org/r/20250408-scx-v2-1-1979fc040903@debian.org Changes in v2: - Use kvfree() on the free path as well. - Link to v1: https://lore.kernel.org/r/20250407-scx-v1-1-774ba74a2c17@debian.org --- kernel/sched/ext.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 66bcd40a28ca1..db9af6a3c04fd 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -4623,7 +4623,7 @@ static void scx_ops_bypass(bool bypass) static void free_exit_info(struct scx_exit_info *ei) { - kfree(ei->dump); + kvfree(ei->dump); kfree(ei->msg); kfree(ei->bt); kfree(ei); @@ -4639,7 +4639,7 @@ static struct scx_exit_info *alloc_exit_info(size_t exit_dump_len) ei->bt = kcalloc(SCX_EXIT_BT_LEN, sizeof(ei->bt[0]), GFP_KERNEL); ei->msg = kzalloc(SCX_EXIT_MSG_LEN, GFP_KERNEL); - ei->dump = kzalloc(exit_dump_len, GFP_KERNEL); + ei->dump = kvzalloc(exit_dump_len, GFP_KERNEL); if (!ei->bt || !ei->msg || !ei->dump) { free_exit_info(ei); --- base-commit: 0af2f6be1b4281385b618cb86ad946eded089ac8 change-id: 20250407-scx-11dbf94803c3 Best regards, -- Breno Leitao <leitao(a)debian.org>

4 months, 2 weeks

3
2
0 0

[PATCH v2] sched/deadline: Fix race in push_dl_task

by Harshit Agarwal

This fix is the deadline version of the change made to the rt scheduler titled: "sched/rt: Fix race in push_rt_task". Here is the summary of the issue: When a CPU chooses to call push_dl_task and picks a task to push to another CPU's runqueue then it will call find_lock_later_rq method which would take a double lock on both CPUs' runqueues. If one of the locks aren't readily available, it may lead to dropping the current runqueue lock and reacquiring both the locks at once. During this window it is possible that the task is already migrated and is running on some other CPU. These cases are already handled. However, if the task is migrated and has already been executed and another CPU is now trying to wake it up (ttwu) such that it is queued again on the runqeue (on_rq is 1) and also if the task was run by the same CPU, then the current checks will pass even though the task was migrated out and is no longer in the pushable tasks list. Please go through the original change for more details on the issue. In this fix, after the lock is obtained inside the find_lock_later_rq we ensure that the task is still at the head of pushable tasks list. Also removed some checks that are no longer needed with the addition this new check. However, the check of pushable tasks list only applies when find_lock_later_rq is called by push_dl_task. For the other caller i.e. dl_task_offline_migration, we use the existing checks. Signed-off-by: Harshit Agarwal <harshit(a)nutanix.com> Cc: stable(a)vger.kernel.org --- Changes in v2: - As per Juri's suggestion, moved the check inside find_lock_later_rq similar to rt change. Here we distinguish among the push_dl_task caller vs dl_task_offline_migration by checking if the task is throttled or not. - Fixed the commit message to refer to the rt change by title. - Link to v1: https://lore.kernel.org/lkml/20250307204255.60640-1-harshit@nutanix.com/ --- kernel/sched/deadline.c | 66 ++++++++++++++++++++++++++--------------- 1 file changed, 42 insertions(+), 24 deletions(-) diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 38e4537790af..2366801b4557 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -2621,6 +2621,25 @@ static int find_later_rq(struct task_struct *task) return -1; } +static struct task_struct *pick_next_pushable_dl_task(struct rq *rq) +{ + struct task_struct *p; + + if (!has_pushable_dl_tasks(rq)) + return NULL; + + p = __node_2_pdl(rb_first_cached(&rq->dl.pushable_dl_tasks_root)); + + WARN_ON_ONCE(rq->cpu != task_cpu(p)); + WARN_ON_ONCE(task_current(rq, p)); + WARN_ON_ONCE(p->nr_cpus_allowed <= 1); + + WARN_ON_ONCE(!task_on_rq_queued(p)); + WARN_ON_ONCE(!dl_task(p)); + + return p; +} + /* Locks the rq it finds */ static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq) { @@ -2648,12 +2667,30 @@ static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq) /* Retry if something changed. */ if (double_lock_balance(rq, later_rq)) { - if (unlikely(task_rq(task) != rq || + /* + * We had to unlock the run queue. In the meantime, + * task could have migrated already or had its affinity + * changed. + * It is possible the task was scheduled, set + * "migrate_disabled" and then got preempted, so we must + * check the task migration disable flag here too. + * For throttled task (dl_task_offline_migration), we + * check if the task is migrated to a different rq or + * is not a dl task anymore. + * For the non-throttled task (push_dl_task), the check + * to ensure that this task is still at the head of the + * pushable tasks list is enough. + */ + if (unlikely(is_migration_disabled(task) || !cpumask_test_cpu(later_rq->cpu, &task->cpus_mask) || - task_on_cpu(rq, task) || - !dl_task(task) || - is_migration_disabled(task) || - !task_on_rq_queued(task))) { + (task->dl.dl_throttled && + (task_rq(task) != rq || + task_on_cpu(rq, task) || + !dl_task(task) || + !task_on_rq_queued(task))) || + (!task->dl.dl_throttled && + task != pick_next_pushable_dl_task(rq)))) { + double_unlock_balance(rq, later_rq); later_rq = NULL; break; @@ -2676,25 +2713,6 @@ static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq) return later_rq; } -static struct task_struct *pick_next_pushable_dl_task(struct rq *rq) -{ - struct task_struct *p; - - if (!has_pushable_dl_tasks(rq)) - return NULL; - - p = __node_2_pdl(rb_first_cached(&rq->dl.pushable_dl_tasks_root)); - - WARN_ON_ONCE(rq->cpu != task_cpu(p)); - WARN_ON_ONCE(task_current(rq, p)); - WARN_ON_ONCE(p->nr_cpus_allowed <= 1); - - WARN_ON_ONCE(!task_on_rq_queued(p)); - WARN_ON_ONCE(!dl_task(p)); - - return p; -} - /* * See if the non running -deadline tasks on this rq * can be sent to some other CPU where they can preempt -- 2.39.3

4 months, 2 weeks

2
2
0 0

[PATCH] irqchip/loongson-liointc: Support to set IRQ_TYPE_EDGE_BOTH

by Huacai Chen

Some peripheral subsystems request IRQ_TYPE_EDGE_BOTH interrupt type and report request failures on LIOINTC. To avoid such failures we support to set IRQ_TYPE_EDGE_BOTH type on LIOINTC, by setting LIOINTC_REG_INTC_EDGE to true and keep LIOINTC_REG_INTC_POL as is. Cc: stable(a)vger.kernel.org Signed-off-by: Yinbo Zhu <zhuyinbo(a)loongson.cn> Signed-off-by: Huacai Chen <chenhuacai(a)loongson.cn> --- drivers/irqchip/irq-loongson-liointc.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/irqchip/irq-loongson-liointc.c b/drivers/irqchip/irq-loongson-liointc.c index 2b1bd4a96665..c0c8ef8d27cf 100644 --- a/drivers/irqchip/irq-loongson-liointc.c +++ b/drivers/irqchip/irq-loongson-liointc.c @@ -128,6 +128,10 @@ static int liointc_set_type(struct irq_data *data, unsigned int type) liointc_set_bit(gc, LIOINTC_REG_INTC_EDGE, mask, false); liointc_set_bit(gc, LIOINTC_REG_INTC_POL, mask, true); break; + case IRQ_TYPE_EDGE_BOTH: + liointc_set_bit(gc, LIOINTC_REG_INTC_EDGE, mask, true); + /* Requester need "both", keep LIOINTC_REG_INTC_POL as is */ + break; case IRQ_TYPE_EDGE_RISING: liointc_set_bit(gc, LIOINTC_REG_INTC_EDGE, mask, true); liointc_set_bit(gc, LIOINTC_REG_INTC_POL, mask, false); -- 2.47.1

4 months, 2 weeks

3
7
0 0

[PATCH] tpm: Mask TPM RC in tpm2_start_auth_session()

by Jarkko Sakkinen

tpm2_start_auth_session() does not mask TPM RC correctly from the callers: [ 28.766528] tpm tpm0: A TPM error (2307) occurred start auth session Process TPM RCs inside tpm2_start_auth_session(), and map them to POSIX error codes. Cc: stable(a)vger.kernel.org # v6.10+ Fixes: 699e3efd6c64 ("tpm: Add HMAC session start and end functions") Reported-by: Herbert Xu <herbert(a)gondor.apana.org.au> Closes: https://lore.kernel.org/linux-integrity/Z_NgdRHuTKP6JK--@gondor.apana.org.a… Signed-off-by: Jarkko Sakkinen <jarkko(a)kernel.org> --- drivers/char/tpm/tpm2-sessions.c | 34 ++++++++++++++++---------------- include/linux/tpm.h | 1 + 2 files changed, 18 insertions(+), 17 deletions(-) diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c index 3f89635ba5e8..1ed23375e4cb 100644 --- a/drivers/char/tpm/tpm2-sessions.c +++ b/drivers/char/tpm/tpm2-sessions.c @@ -40,11 +40,6 @@ * * These are the usage functions: * - * tpm2_start_auth_session() which allocates the opaque auth structure - * and gets a session from the TPM. This must be called before - * any of the following functions. The session is protected by a - * session_key which is derived from a random salt value - * encrypted to the NULL seed. * tpm2_end_auth_session() kills the session and frees the resources. * Under normal operation this function is done by * tpm_buf_check_hmac_response(), so this is only to be used on @@ -963,16 +958,13 @@ static int tpm2_load_null(struct tpm_chip *chip, u32 *null_key) } /** - * tpm2_start_auth_session() - create a HMAC authentication session with the TPM - * @chip: the TPM chip structure to create the session with + * tpm2_start_auth_session() - Create an a HMAC authentication session + * @chip: A TPM chip * - * This function loads the NULL seed from its saved context and starts - * an authentication session on the null seed, fills in the - * @chip->auth structure to contain all the session details necessary - * for performing the HMAC, encrypt and decrypt operations and - * returns. The NULL seed is flushed before this function returns. + * Loads the ephemeral key (null seed), and starts an HMAC authenticated + * session. The null seed is flushed before the return. * - * Return: zero on success or actual error encountered. + * Returns zero on success, or a POSIX error code. */ int tpm2_start_auth_session(struct tpm_chip *chip) { @@ -1024,11 +1016,19 @@ int tpm2_start_auth_session(struct tpm_chip *chip) /* hash algorithm for session */ tpm_buf_append_u16(&buf, TPM_ALG_SHA256); - rc = tpm_transmit_cmd(chip, &buf, 0, "start auth session"); + rc = tpm_transmit_cmd(chip, &buf, 0, "StartAuthSession"); tpm2_flush_context(chip, null_key); - - if (rc == TPM2_RC_SUCCESS) - rc = tpm2_parse_start_auth_session(auth, &buf); + switch (rc) { + case TPM2_RC_SUCCESS: + break; + case TPM2_RC_SESSION_MEMORY: + rc = -ENOMEM; + goto out; + default: + rc = -EFAULT; + goto out; + } + rc = tpm2_parse_start_auth_session(auth, &buf); tpm_buf_destroy(&buf); diff --git a/include/linux/tpm.h b/include/linux/tpm.h index 6c3125300c00..c1d3d60b416f 100644 --- a/include/linux/tpm.h +++ b/include/linux/tpm.h @@ -257,6 +257,7 @@ enum tpm2_return_codes { TPM2_RC_TESTING = 0x090A, /* RC_WARN */ TPM2_RC_REFERENCE_H0 = 0x0910, TPM2_RC_RETRY = 0x0922, + TPM2_RC_SESSION_MEMORY = 0x0903, }; enum tpm2_command_codes { -- 2.39.5

4 months, 2 weeks

2
10
0 0

[REGRESSION] stable-rc/linux-6.12.y: (build) in vmlinux (scripts/Makefile.vmlinux:34) [logspec:kbuild,kbuild.co...

by KernelCI bot

Hello, New build issue found on stable-rc/linux-6.12.y: --- in vmlinux (scripts/Makefile.vmlinux:34) [logspec:kbuild,kbuild.compiler.linker_error] --- - dashboard: https://d.kernelci.org/i/maestro:044a06526d293c2801fdbdc2f440e46bd3b51a52 - giturl: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git - commit HEAD: 8e9508dd93587658f8f8116bc709aeb272144427 Log excerpt: ===================================================== ld.lld: error: ./arch/arm/kernel/vmlinux.lds:36: ( expected, but got } >>> __vectors_lma = .; OVERLAY 0xffff0000 : AT(__vectors_lma) { .vectors { OVERLAY_KEEP(*(.vectors)) } .vectors.bhb.loop8 { OVERLAY_KEEP(*(.vectors.bhb.loop8)) } .vectors.bhb.bpiall { OVERLAY_KEEP(*(.vectors.bhb.bpiall)) } } __vectors_start = LOADADDR(.vectors); __vectors_end = LOADADDR(.vectors) + SIZEOF(.vectors); __vectors_bhb_loop8_start = LOADADDR(.vectors.bhb.loop8); __vectors_bhb_loop8_end = LOADADDR(.vectors.bhb.loop8) + SIZEOF(.vectors.bhb.loop8); __vectors_bhb_bpiall_start = LOADADDR(.vectors.bhb.bpiall); __vectors_bhb_bpiall_end = LOADADDR(.vectors.bhb.bpiall) + SIZEOF(.vectors.bhb.bpiall); . = __vectors_lma + SIZEOF(.vectors) + SIZEOF(.vectors.bhb.loop8) + SIZEOF(.vectors.bhb.bpiall); __stubs_lma = .; .stubs ADDR(.vectors) + 0x1000 : AT(__stubs_lma) { *(.stubs) } __stubs_start = LOADADDR(.stubs); __stubs_end = LOADADDR(.stubs) + SIZEOF(.stubs); . = __stubs_lma + SIZEOF(.stubs); PROVIDE(vector_fiq_offset = vector_fiq - ADDR(.vectors)); >>> ^ ===================================================== # Builds where the incident occurred: ## defconfig+allmodconfig+CONFIG_FRAME_WARN=2048 on (arm): - compiler: clang-17 - dashboard: https://d.kernelci.org/build/maestro:67f50be06fa43d168f278ccc #kernelci issue maestro:044a06526d293c2801fdbdc2f440e46bd3b51a52 Reported-by: kernelci.org bot <bot(a)kernelci.org> -- This is an experimental report format. Please send feedback in! Talk to us at kernelci(a)lists.linux.dev Made with love by the KernelCI team - https://kernelci.org

4 months, 2 weeks

1
0
0 0

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