linux-kernel - Re: [PATCH uprobe, thp 3/4] uprobe: support huge page by only splitting the pmd

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Date:   Thu, 30 May 2019 05:08:43 -0600
From:   William Kucharski <william.kucharski@...cle.com>
To:     Song Liu <songliubraving@...com>
Cc:     LKML <linux-kernel@...r.kernel.org>, Linux-MM <linux-mm@...ck.org>,
        namit@...are.com, Peter Zijlstra <peterz@...radead.org>,
        oleg@...hat.com, Steven Rostedt <rostedt@...dmis.org>,
        mhiramat@...nel.org, Matthew Wilcox <matthew.wilcox@...cle.com>,
        kirill.shutemov@...ux.intel.com, kernel-team@...com,
        Chad Mynhier <chad.mynhier@...cle.com>, mike.kravetz@...cle.com
Subject: Re: [PATCH uprobe, thp 3/4] uprobe: support huge page by only
 splitting the pmd

Is there any reason to worry about supporting PUD-sized uprobe pages if
CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD is defined? I would prefer
not to bake in the assumption that "huge" means PMD-sized and more than
it already is.

For example, if CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD is configured,
mm_address_trans_huge() should either make the call to pud_trans_huge()
if appropriate, or a VM_BUG_ON_PAGE should be added in case the routine
is ever called with one.

Otherwise it looks pretty reasonable to me.

    -- Bill