From: Catalin Marinas <catalin.marinas@arm.com>
To: Jia He <justin.he@arm.com>
Cc: "Will Deacon" <will@kernel.org>,
"Mark Rutland" <mark.rutland@arm.com>,
"James Morse" <james.morse@arm.com>,
"Marc Zyngier" <maz@kernel.org>,
"Matthew Wilcox" <willy@infradead.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
"Suzuki Poulose" <Suzuki.Poulose@arm.com>,
"Punit Agrawal" <punitagrawal@gmail.com>,
"Anshuman Khandual" <anshuman.khandual@arm.com>,
"Alex Van Brunt" <avanbrunt@nvidia.com>,
"Robin Murphy" <robin.murphy@arm.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Jérôme Glisse" <jglisse@redhat.com>,
"Ralph Campbell" <rcampbell@nvidia.com>,
hejianet@gmail.com, "Kaly Xin" <Kaly.Xin@arm.com>
Subject: Re: [PATCH v5 3/3] mm: fix double page fault on arm64 if PTE_AF is cleared
Date: Thu, 19 Sep 2019 17:42:06 +0100 [thread overview]
Message-ID: <20190919164206.GE6472@arrakis.emea.arm.com> (raw)
In-Reply-To: <20190919161204.142796-4-justin.he@arm.com>
On Fri, Sep 20, 2019 at 12:12:04AM +0800, Jia He wrote:
> @@ -2152,7 +2163,29 @@ static inline void cow_user_page(struct page *dst, struct page *src, unsigned lo
> */
> if (unlikely(!src)) {
> void *kaddr = kmap_atomic(dst);
> - void __user *uaddr = (void __user *)(va & PAGE_MASK);
> + void __user *uaddr = (void __user *)(addr & PAGE_MASK);
> + pte_t entry;
> +
> + /* On architectures with software "accessed" bits, we would
> + * take a double page fault, so mark it accessed here.
> + */
> + if (arch_faults_on_old_pte() && !pte_young(vmf->orig_pte)) {
> + spin_lock(vmf->ptl);
> + if (likely(pte_same(*vmf->pte, vmf->orig_pte))) {
> + entry = pte_mkyoung(vmf->orig_pte);
> + if (ptep_set_access_flags(vma, addr,
> + vmf->pte, entry, 0))
> + update_mmu_cache(vma, addr, vmf->pte);
> + } else {
> + /* Other thread has already handled the fault
> + * and we don't need to do anything. If it's
> + * not the case, the fault will be triggered
> + * again on the same address.
> + */
> + return -1;
> + }
> + spin_unlock(vmf->ptl);
Returning with the spinlock held doesn't normally go very well ;).
--
Catalin
next prev parent reply other threads:[~2019-09-19 16:42 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-19 16:12 [PATCH v5 0/3] fix double page fault on arm64 Jia He
2019-09-19 16:12 ` [PATCH v5 1/3] arm64: cpufeature: introduce helper cpu_has_hw_af() Jia He
2019-09-19 16:36 ` Catalin Marinas
2019-09-20 1:14 ` Justin He (Arm Technology China)
2019-09-19 16:12 ` [PATCH v5 2/3] arm64: mm: implement arch_faults_on_old_pte() on arm64 Jia He
2019-09-19 16:12 ` [PATCH v5 3/3] mm: fix double page fault on arm64 if PTE_AF is cleared Jia He
2019-09-19 16:42 ` Catalin Marinas [this message]
2019-09-20 1:13 ` Justin He (Arm Technology China)
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