From: Oleg Nesterov <oleg@redhat.com>
To: Song Liu <songliubraving@fb.com>
Cc: lkml <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"matthew.wilcox@oracle.com" <matthew.wilcox@oracle.com>,
"kirill.shutemov@linux.intel.com"
<kirill.shutemov@linux.intel.com>,
Kernel Team <Kernel-team@fb.com>,
"william.kucharski@oracle.com" <william.kucharski@oracle.com>,
"srikar@linux.vnet.ibm.com" <srikar@linux.vnet.ibm.com>
Subject: Re: [PATCH v10 3/4] mm, thp: introduce FOLL_SPLIT_PMD
Date: Thu, 1 Aug 2019 17:04:33 +0200 [thread overview]
Message-ID: <20190801150432.GC31538@redhat.com> (raw)
In-Reply-To: <04FB43C3-6E2B-4868-B9D5-C00342DA5C6F@fb.com>
On 07/31, Song Liu wrote:
>
> > On Jul 31, 2019, at 8:18 AM, Oleg Nesterov <oleg@redhat.com> wrote:
> >
> > Now, I don't understand why do we need pmd_trans_unstable() after
> > split_huge_pmd(huge-zero-pmd), but whatever reason we have, why can't we
> > unify both cases?
> >
> > IOW, could you explain why the path below is wrong?
>
> I _think_ the following patch works (haven't fully tested yet). But I am not
> sure whether this is the best. By separating the two cases, we don't duplicate
> much code. And it is clear that the two cases are handled differently.
> Therefore, I would prefer to keep these separate for now.
I disagree. I think this separation makes the code less readable/understandable.
Exactly because it handles two cases differently and it is absolutely not clear
why.
But I can't argue, please forget.
Oleg.
next prev parent reply other threads:[~2019-08-01 15:04 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-30 5:23 [PATCH v10 0/4] THP aware uprobe Song Liu
2019-07-30 5:23 ` [PATCH v10 1/4] mm: move memcmp_pages() and pages_identical() Song Liu
2019-07-30 5:23 ` [PATCH v10 2/4] uprobe: use original page when all uprobes are removed Song Liu
2019-07-30 16:58 ` Oleg Nesterov
2019-07-30 5:23 ` [PATCH v10 3/4] mm, thp: introduce FOLL_SPLIT_PMD Song Liu
2019-07-30 16:11 ` Oleg Nesterov
2019-07-30 17:42 ` Song Liu
2019-07-31 15:18 ` Oleg Nesterov
2019-07-31 17:10 ` Song Liu
2019-08-01 15:04 ` Oleg Nesterov [this message]
2019-07-30 5:23 ` [PATCH v10 4/4] uprobe: use FOLL_SPLIT_PMD instead of FOLL_SPLIT Song Liu
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