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From: Rik van Riel <riel@fb.com>
To: Song Liu <songliubraving@fb.com>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>
Cc: "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>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>
Subject: Re: [PATCH v3 6/6] mm,thp: handle writes to file with THP in pagecache
Date: Thu, 20 Jun 2019 01:39:29 +0000	[thread overview]
Message-ID: <9ec5787861152deb1c6c6365b593343b3aef18d4.camel@fb.com> (raw)
In-Reply-To: <20190619062424.3486524-7-songliubraving@fb.com>

On Tue, 2019-06-18 at 23:24 -0700, Song Liu wrote:

> index 8563339041f6..bab8d9eef46c 100644
> --- a/mm/truncate.c
> +++ b/mm/truncate.c
> @@ -790,7 +790,11 @@ EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
>  void truncate_pagecache(struct inode *inode, loff_t newsize)
>  {
>  	struct address_space *mapping = inode->i_mapping;
> -	loff_t holebegin = round_up(newsize, PAGE_SIZE);
> +	loff_t holebegin;
> +
> +	/* if non-shmem file has thp, truncate the whole file */
> +	if (filemap_nr_thps(mapping))
> +		newsize = 0;
>  

I don't get it. Sometimes truncate is used to
increase the size of a file, or to change it
to a non-zero size.

Won't forcing the newsize to zero break applications,
when the file is truncated to a different size than
they expect?


  reply	other threads:[~2019-06-20  1:39 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-19  6:24 [PATCH v3 0/6] Enable THP for text section of non-shmem files Song Liu
2019-06-19  6:24 ` [PATCH v3 1/6] filemap: check compound_head(page)->mapping in filemap_fault() Song Liu
2019-06-19  6:24 ` [PATCH v3 2/6] filemap: update offset check " Song Liu
2019-06-20  1:04   ` Rik van Riel
2019-06-19  6:24 ` [PATCH v3 3/6] mm,thp: stats for file backed THP Song Liu
2019-06-19  6:24 ` [PATCH v3 4/6] khugepaged: rename collapse_shmem() and khugepaged_scan_shmem() Song Liu
2019-06-20  1:05   ` Rik van Riel
2019-06-19  6:24 ` [PATCH v3 5/6] mm,thp: add read-only THP support for (non-shmem) FS Song Liu
2019-06-19  6:24 ` [PATCH v3 6/6] mm,thp: handle writes to file with THP in pagecache Song Liu
2019-06-20  1:39   ` Rik van Riel [this message]
2019-06-20  2:10     ` Song Liu
2019-06-20 13:00       ` Rik van Riel
2019-06-20 13:55       ` William Kucharski
2019-06-19  6:51 ` [PATCH v3 0/6] Enable THP for text section of non-shmem files Michal Hocko

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