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From: Chintan Pandya <cpandya@codeaurora.org>
To: "joro@8bytes.org" <joro@8bytes.org>
Cc: "guohanjun@huawei.com" <guohanjun@huawei.com>,
	"Hocko, Michal" <MHocko@suse.com>,
	"Kani, Toshi" <toshi.kani@hpe.com>,
	"wxf.wang@hisilicon.com" <wxf.wang@hisilicon.com>,
	"catalin.marinas@arm.com" <catalin.marinas@arm.com>,
	"x86@kernel.org" <x86@kernel.org>,
	"will.deacon@arm.com" <will.deacon@arm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"willy@infradead.org" <willy@infradead.org>,
	"hpa@zytor.com" <hpa@zytor.com>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"bp@suse.de" <bp@suse.de>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v2 2/2] x86/mm: implement free pmd/pte page interfaces
Date: Fri, 27 Apr 2018 19:12:57 +0530	[thread overview]
Message-ID: <fb4771ca-694b-8a52-d239-1c730617600b@codeaurora.org> (raw)
In-Reply-To: <20180427124828.GW15462@8bytes.org>



On 4/27/2018 6:18 PM, joro@8bytes.org wrote:
> On Fri, Apr 27, 2018 at 05:22:28PM +0530, Chintan Pandya wrote:
>> I'm bit confused here. Are you pointing to race within ioremap/vmalloc
>> framework while updating the page table or race during tlb ops. Since
>> later is arch dependent, I would not comment. But if the race being
>> discussed here while altering page tables, I'm not on the same page.
> 
> The race condition is between hardware and software. It is not
> sufficient to just remove the software references to the page that is
> about to be freed (by clearing the PMD/PUD), also the hardware
> references in the page-walk cache need to be removed with a TLB flush.
> Otherwise the hardware can use the freed (and possibly reused) page to
> establish new TLB entries.

Sure ! This is my understanding too (from arm64 context).

> 
> 
> 
> 	Joerg
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 

Chintan
-- 
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center,
Inc. is a member of the Code Aurora Forum, a Linux Foundation
Collaborative Project

  reply	other threads:[~2018-04-27 13:43 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-14 18:01 [PATCH v2 0/2] fix memory leak / panic in ioremap huge pages Toshi Kani
2018-03-14 18:01 ` [PATCH v2 1/2] mm/vmalloc: Add interfaces to free unmapped page table Toshi Kani
2018-03-14 22:38   ` Andrew Morton
2018-03-15 14:27     ` Kani, Toshi
2018-03-14 18:01 ` [PATCH v2 2/2] x86/mm: implement free pmd/pte page interfaces Toshi Kani
2018-03-15  7:39   ` Chintan Pandya
2018-03-15 14:51     ` Kani, Toshi
2018-04-26 14:19   ` Joerg Roedel
2018-04-26 16:21     ` Kani, Toshi
2018-04-26 17:23       ` joro
2018-04-26 17:49         ` Kani, Toshi
2018-04-26 20:07           ` joro
2018-04-26 22:30             ` Kani, Toshi
2018-04-27  7:37               ` joro
2018-04-27 11:39                 ` Michal Hocko
2018-04-27 11:46                   ` joro
2018-04-27 11:52                 ` Chintan Pandya
2018-04-27 12:48                   ` joro
2018-04-27 13:42                     ` Chintan Pandya [this message]
2018-04-27 14:31                 ` Kani, Toshi
2018-04-28  9:02                   ` joro
2018-04-28 20:54                     ` Kani, Toshi
2018-04-30  7:30                       ` Chintan Pandya
2018-04-30 13:43                         ` Kani, Toshi

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