linux-kernel - Re: [PATCH] mm: madvise: return correct bytes advised with process

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Message-ID: <8758f360-0c6f-28bb-8483-342ad808865f@quicinc.com>
Date:   Thu, 10 Mar 2022 13:55:26 +0530
From:   Charan Teja Kalla <quic_charante@...cinc.com>
To:     Minchan Kim <minchan@...nel.org>
CC:     <akpm@...ux-foundation.org>, <yuehaibing@...wei.com>,
        <sfr@...b.auug.org.au>, <rientjes@...gle.com>,
        <edgararriaga@...gle.com>, <mhocko@...e.com>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: madvise: return correct bytes advised with
 process_madvise


Thanks Minchan for your comment!!
On 3/9/2022 10:17 PM, Minchan Kim wrote:
>> @@ -1426,15 +1426,21 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec,
>>  
>>  	while (iov_iter_count(&iter)) {
>>  		iovec = iov_iter_iovec(&iter);
>> +		/*
>> +		 * Even when [start, end) passed to do_madvise covers
>> +		 * some unmapped addresses, it continues processing with
>> +		 * returning ENOMEM at the end. Thus consider the range
>> +		 * as processed when do_madvise() returns ENOMEM.
>> +		 * This makes process_madvise() never returns ENOMEM.
>> +		 */
> Looks like that this patch has two things. first, returns processed
> bytes instead of error in case of error. Second, keep working on
> rest vmas on -ENOMEM due to unmapped hole.
> 
> First thing totally makes sense to me(that's exactly I wanted to
> do but somehow missed) so it should go stable tree. However,
> second stuff might be arguble so it would be great if you split
> the patch.

Sure, then will split the patch in V2.

>