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From: Hugh Dickins <hughd@google.com>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Hugh Dickins <hughd@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Yang Shi <shy828301@gmail.com>,
	Wang Yugui <wangyugui@e16-tech.com>,
	Matthew Wilcox <willy@infradead.org>,
	Alistair Popple <apopple@nvidia.com>,
	Ralph Campbell <rcampbell@nvidia.com>, Zi Yan <ziy@nvidia.com>,
	Peter Xu <peterx@redhat.com>, Will Deacon <will@kernel.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 06/11] mm: page_vma_mapped_walk(): crossing page table boundary
Date: Thu, 10 Jun 2021 16:02:47 -0700 (PDT)	[thread overview]
Message-ID: <4679ec74-80a-ed13-e58e-654911fbab28@google.com> (raw)
In-Reply-To: <20210610093203.x42jpifagiavmrlp@box.shutemov.name>

On Thu, 10 Jun 2021, Kirill A. Shutemov wrote:
> On Wed, Jun 09, 2021 at 11:44:10PM -0700, Hugh Dickins wrote:
> > page_vma_mapped_walk() cleanup: adjust the test for crossing page table
> > boundary - I believe pvmw->address is always page-aligned, but nothing
> > else here assumed that;
> 
> Maybe we should just get it aligned instead? (PMD_SIZE - PAGE_SIZE) is not
> most obvious mask calculation.

Would you prefer it with another line of comment after the
/* Did we cross page table boundary? */

Maybe,
/* Is address always page-aligned? No need to assume that. */

I just don't see the point in forcing alignment when the test is good
(and don't know for sure whether address is always aligned there or not).

I prefer to leave it as is, just letting the commit message document it.

> 
> > and remember to reset pvmw->pte to NULL after
> > unmapping the page table, though I never saw any bug from that.
> 
> Okay, it's fair enough.

Thanks,
Hugh

  reply	other threads:[~2021-06-10 23:04 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-10  6:31 [PATCH 00/11] mm: page_vma_mapped_walk() cleanup and THP fixes Hugh Dickins
2021-06-10  6:31 ` Hugh Dickins
2021-06-10  6:34 ` [PATCH 01/11] mm: page_vma_mapped_walk(): use page for pvmw->page Hugh Dickins
2021-06-10  6:34   ` Hugh Dickins
2021-06-10  8:12   ` Alistair Popple
2021-06-10  8:55   ` Kirill A. Shutemov
2021-06-10 14:14     ` Peter Xu
2021-06-10 22:35       ` Hugh Dickins
2021-06-10  6:36 ` [PATCH 02/11] mm: page_vma_mapped_walk(): settle PageHuge on entry Hugh Dickins
2021-06-10  6:36   ` Hugh Dickins
2021-06-10  8:57   ` Kirill A. Shutemov
2021-06-10 14:17   ` Peter Xu
2021-06-10 22:45     ` Hugh Dickins
2021-06-10  6:38 ` [PATCH 03/11] mm: page_vma_mapped_walk(): use pmd_read_atomic() Hugh Dickins
2021-06-10  6:38   ` Hugh Dickins
2021-06-10  9:06   ` Kirill A. Shutemov
2021-06-10 12:15     ` Jason Gunthorpe
2021-06-11  6:37       ` Hugh Dickins
2021-06-11 15:36         ` Jason Gunthorpe
2021-06-11 19:05           ` Hugh Dickins
2021-06-11 19:05             ` Hugh Dickins
2021-06-11 19:42             ` Jason Gunthorpe
2021-06-15  9:46               ` Will Deacon
2021-06-16  0:42                 ` Jason Gunthorpe
2021-06-16 10:27                   ` Will Deacon
2021-06-11 19:33           ` Hugh Dickins
2021-06-11 19:33             ` Hugh Dickins
2021-06-10  6:40 ` [PATCH 04/11] mm: page_vma_mapped_walk(): use pmde for *pvmw->pmd Hugh Dickins
2021-06-10  6:40   ` Hugh Dickins
2021-06-10  9:10   ` Kirill A. Shutemov
2021-06-10 14:31   ` Peter Xu
2021-06-10  6:42 ` [PATCH 05/11] mm: page_vma_mapped_walk(): prettify PVMW_MIGRATION block Hugh Dickins
2021-06-10  6:42   ` Hugh Dickins
2021-06-10  9:16   ` Kirill A. Shutemov
2021-06-10 14:48   ` Peter Xu
2021-06-10  6:44 ` [PATCH 06/11] mm: page_vma_mapped_walk(): crossing page table boundary Hugh Dickins
2021-06-10  6:44   ` Hugh Dickins
2021-06-10  9:32   ` Kirill A. Shutemov
2021-06-10 23:02     ` Hugh Dickins [this message]
2021-06-11 11:23       ` Kirill A. Shutemov
2021-06-10  6:46 ` [PATCH 07/11] mm: page_vma_mapped_walk(): add a level of indentation Hugh Dickins
2021-06-10  6:46   ` Hugh Dickins
2021-06-10  9:34   ` Kirill A. Shutemov
2021-06-10  6:48 ` [PATCH 08/11] mm: page_vma_mapped_walk(): use goto instead of while (1) Hugh Dickins
2021-06-10  6:48   ` Hugh Dickins
2021-06-10  9:39   ` Kirill A. Shutemov
2021-06-10  6:50 ` [PATCH 09/11] mm: page_vma_mapped_walk(): get vma_address_end() earlier Hugh Dickins
2021-06-10  6:50   ` Hugh Dickins
2021-06-10  9:40   ` Kirill A. Shutemov
2021-06-10  6:52 ` [PATCH 10/11] mm/thp: fix page_vma_mapped_walk() if THP mapped by ptes Hugh Dickins
2021-06-10  6:52   ` Hugh Dickins
2021-06-10  9:42   ` Kirill A. Shutemov
2021-06-10  6:54 ` [PATCH 11/11] mm/thp: another PVMW_SYNC fix in page_vma_mapped_walk() Hugh Dickins
2021-06-10  6:54   ` Hugh Dickins
2021-06-10  9:43   ` Kirill A. Shutemov
2021-06-11 18:29     ` Hugh Dickins
2021-06-11 18:29       ` Hugh Dickins

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