From: zanussi@kernel.org
To: LKML <linux-kernel@vger.kernel.org>,
linux-rt-users <linux-rt-users@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
Carsten Emde <C.Emde@osadl.org>, John Kacur <jkacur@redhat.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Daniel Wagner <wagi@monom.org>, Tom Zanussi <zanussi@kernel.org>
Subject: [PATCH RT 16/25] Revert "ARM: Initialize split page table locks for vector page"
Date: Fri, 21 Feb 2020 15:24:44 -0600 [thread overview]
Message-ID: <0862e594250ce236c9e324e7fc3ff1eee44925b2.1582320278.git.zanussi@kernel.org> (raw)
In-Reply-To: <cover.1582320278.git.zanussi@kernel.org>
In-Reply-To: <cover.1582320278.git.zanussi@kernel.org>
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
v4.14.170-rt75-rc1 stable review patch.
If anyone has any objections, please let me know.
-----------
[ Upstream commit 247074c44d8c3e619dfde6404a52295d8d671d38 ]
I'm dropping this patch, with its original description:
|ARM: Initialize split page table locks for vector page
|
|Without this patch, ARM can not use SPLIT_PTLOCK_CPUS if
|PREEMPT_RT_FULL=y because vectors_user_mapping() creates a
|VM_ALWAYSDUMP mapping of the vector page (address 0xffff0000), but no
|ptl->lock has been allocated for the page. An attempt to coredump
|that page will result in a kernel NULL pointer dereference when
|follow_page() attempts to lock the page.
|
|The call tree to the NULL pointer dereference is:
|
| do_notify_resume()
| get_signal_to_deliver()
| do_coredump()
| elf_core_dump()
| get_dump_page()
| __get_user_pages()
| follow_page()
| pte_offset_map_lock() <----- a #define
| ...
| rt_spin_lock()
|
|The underlying problem is exposed by mm-shrink-the-page-frame-to-rt-size.patch.
The patch named mm-shrink-the-page-frame-to-rt-size.patch was dropped
from the RT queue once the SPLIT_PTLOCK_CPUS feature (in a slightly
different shape) went upstream (somewhere between v3.12 and v3.14).
I can see that the patch still allocates a lock which wasn't there
before. However I can't trigger a kernel oops like described in the
patch by triggering a coredump.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
---
arch/arm/kernel/process.c | 24 ------------------------
1 file changed, 24 deletions(-)
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index cf4e1452d4b4..d96714e1858c 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -325,30 +325,6 @@ unsigned long arch_randomize_brk(struct mm_struct *mm)
}
#ifdef CONFIG_MMU
-/*
- * CONFIG_SPLIT_PTLOCK_CPUS results in a page->ptl lock. If the lock is not
- * initialized by pgtable_page_ctor() then a coredump of the vector page will
- * fail.
- */
-static int __init vectors_user_mapping_init_page(void)
-{
- struct page *page;
- unsigned long addr = 0xffff0000;
- pgd_t *pgd;
- pud_t *pud;
- pmd_t *pmd;
-
- pgd = pgd_offset_k(addr);
- pud = pud_offset(pgd, addr);
- pmd = pmd_offset(pud, addr);
- page = pmd_page(*(pmd));
-
- pgtable_page_ctor(page);
-
- return 0;
-}
-late_initcall(vectors_user_mapping_init_page);
-
#ifdef CONFIG_KUSER_HELPERS
/*
* The vectors page is always readable from user space for the
--
2.14.1
next prev parent reply other threads:[~2020-02-21 21:25 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-21 21:24 [PATCH RT 00/25] Linux v4.14.170-rt75-rc1 zanussi
2020-02-21 21:24 ` [PATCH RT 01/25] Fix wrong-variable use in irq_set_affinity_notifier zanussi
2020-02-21 21:24 ` [PATCH RT 02/25] x86: preempt: Check preemption level before looking at lazy-preempt zanussi
2020-02-21 21:24 ` [PATCH RT 03/25] sched/deadline: Ensure inactive_timer runs in hardirq context zanussi
2020-02-24 8:33 ` Sebastian Andrzej Siewior
2020-02-25 14:50 ` Juri Lelli
2020-02-21 21:24 ` [PATCH RT 04/25] i2c: hix5hd2: Remove IRQF_ONESHOT zanussi
2020-02-21 21:24 ` [PATCH RT 05/25] i2c: exynos5: " zanussi
2020-02-21 21:24 ` [PATCH RT 06/25] sched: migrate_dis/enable: Use sleeping_lock…() to annotate sleeping points zanussi
2020-02-21 21:24 ` [PATCH RT 07/25] sched: __set_cpus_allowed_ptr: Check cpus_mask, not cpus_ptr zanussi
2020-02-21 21:24 ` [PATCH RT 08/25] sched: Remove dead __migrate_disabled() check zanussi
2020-02-21 21:24 ` [PATCH RT 09/25] sched: migrate disable: Protect cpus_ptr with lock zanussi
2020-02-21 21:24 ` [PATCH RT 10/25] lib/smp_processor_id: Don't use cpumask_equal() zanussi
2020-02-21 21:24 ` [PATCH RT 11/25] futex: Make the futex_hash_bucket spinlock_t again and bring back its old state zanussi
2020-02-21 21:24 ` [PATCH RT 12/25] locking/rtmutex: Clean ->pi_blocked_on in the error case zanussi
2020-02-21 21:24 ` [PATCH RT 13/25] lib/ubsan: Don't seralize UBSAN report zanussi
2020-02-21 21:24 ` [PATCH RT 14/25] kmemleak: Change the lock of kmemleak_object to raw_spinlock_t zanussi
2020-02-21 21:24 ` [PATCH RT 15/25] sched: migrate_enable: Use select_fallback_rq() zanussi
2020-02-24 9:43 ` Sebastian Andrzej Siewior
2020-02-24 15:31 ` Tom Zanussi
2020-02-24 16:05 ` Sebastian Andrzej Siewior
2020-02-24 22:15 ` Scott Wood
2020-02-21 21:24 ` zanussi [this message]
2020-02-21 21:24 ` [PATCH RT 17/25] x86/fpu: Don't cache access to fpu_fpregs_owner_ctx zanussi
2020-02-24 8:55 ` Sebastian Andrzej Siewior
2020-02-24 15:12 ` Tom Zanussi
2020-02-21 21:24 ` [PATCH RT 18/25] locking: Make spinlock_t and rwlock_t a RCU section on RT zanussi
2020-02-21 21:24 ` [PATCH RT 19/25] userfaultfd: Use a seqlock instead of seqcount zanussi
2020-02-24 9:03 ` Sebastian Andrzej Siewior
2020-02-24 15:14 ` Tom Zanussi
2020-02-24 16:17 ` Steven Rostedt
2020-02-21 21:24 ` [PATCH RT 20/25] kmemleak: Cosmetic changes zanussi
2020-02-24 9:12 ` Sebastian Andrzej Siewior
2020-02-24 15:18 ` Tom Zanussi
2020-02-24 15:52 ` Sebastian Andrzej Siewior
2020-02-21 21:24 ` [PATCH RT 21/25] smp: Use smp_cond_func_t as type for the conditional function zanussi
2020-02-24 9:52 ` Sebastian Andrzej Siewior
2020-02-24 15:34 ` Tom Zanussi
2020-02-21 21:24 ` [PATCH RT 22/25] mm/memcontrol: Move misplaced local_unlock_irqrestore() zanussi
2020-02-24 9:55 ` Sebastian Andrzej Siewior
2020-02-21 21:24 ` [PATCH RT 23/25] locallock: Include header for the `current' macro zanussi
2020-02-21 21:24 ` [PATCH RT 24/25] sched: Provide migrate_disable/enable() inlines zanussi
2020-02-21 21:24 ` [PATCH RT 25/25] Linux 4.14.170-rt75-rc1 zanussi
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