linux-kernel - Re: [PATCH v1 4/4] xen/netback: Fix grant copy across page boundary with KASAN

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Message-ID: <dc322a8f-d0ae-dea6-4fe0-cc4d5d14f4d4@citrix.com>
Date:   Fri, 10 Jan 2020 14:27:30 +0000
From:   Sergey Dyasli <sergey.dyasli@...rix.com>
To:     Paul Durrant <pdurrant@...il.com>
CC:     <xen-devel@...ts.xen.org>, <kasan-dev@...glegroups.com>,
        <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        "Dmitry Vyukov" <dvyukov@...gle.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        George Dunlap <george.dunlap@...rix.com>,
        Ross Lagerwall <ross.lagerwall@...rix.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Wei Liu" <wei.liu@...nel.org>,
        "sergey.dyasli@...rix.com >> Sergey Dyasli" 
        <sergey.dyasli@...rix.com>
Subject: Re: [PATCH v1 4/4] xen/netback: Fix grant copy across page boundary
 with KASAN

On 09/01/2020 13:36, Paul Durrant wrote:
> On Wed, 8 Jan 2020 at 15:21, Sergey Dyasli <sergey.dyasli@...rix.com> wrote:
>>
>> From: Ross Lagerwall <ross.lagerwall@...rix.com>
>>
>> When KASAN (or SLUB_DEBUG) is turned on, the normal expectation that
>> allocations are aligned to the next power of 2 of the size does not
>> hold. Therefore, handle grant copies that cross page boundaries.
>>
>> Signed-off-by: Ross Lagerwall <ross.lagerwall@...rix.com>
>> Signed-off-by: Sergey Dyasli <sergey.dyasli@...rix.com>
>> ---
>> RFC --> v1:
>> - Added BUILD_BUG_ON to the netback patch
>> - xenvif_idx_release() now located outside the loop
>>
>> CC: Wei Liu <wei.liu@...nel.org>
>> CC: Paul Durrant <paul@....org>
> [snip]
>>
>> +static void __init __maybe_unused build_assertions(void)
>> +{
>> +       BUILD_BUG_ON(sizeof(struct xenvif_tx_cb) > 48);
>
> FIELD_SIZEOF(struct sk_buff, cb) rather than a magic '48' I think.

The macro got renamed recently, so now it should be:

    sizeof_field(struct sk_buff, cb))

Thanks for the suggestion.

--
Sergey