From: Matthew Wilcox <willy@infradead.org>
To: Yang Shi <shy828301@gmail.com>
Cc: torvalds@linux-foundation.org, arnd@arndb.de, hughd@google.com,
kirill.shutemov@linux.intel.com, naoya.horiguchi@nec.com,
osalvador@suse.de, peterx@redhat.com, ajaygargnsit@gmail.com,
songmuchun@bytedance.com, akpm@linux-foundation.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [UPDATE PATCH] mm: shmem: don't truncate page if memory failure happens
Date: Sun, 14 Nov 2021 15:28:08 +0000 [thread overview]
Message-ID: <YZErCLzSixIwTr6C@casper.infradead.org> (raw)
In-Reply-To: <20211114053221.315753-1-shy828301@gmail.com>
On Sat, Nov 13, 2021 at 09:32:21PM -0800, Yang Shi wrote:
> @@ -2466,7 +2467,18 @@ shmem_write_begin(struct file *file, struct address_space *mapping,
> return -EPERM;
> }
>
> - return shmem_getpage(inode, index, pagep, SGP_WRITE);
> + ret = shmem_getpage(inode, index, pagep, SGP_WRITE);
> +
> + if (ret)
> + return ret;
> +
> + if (*pagep && PageHWPoison(*pagep)) {
> + unlock_page(*pagep);
> + put_page(*pagep);
> + ret = -EIO;
You definitely need to add:
*pagep = NULL;
I'm not entirely convinced that you need the conditional on '*pagep'.
If we returned 0, there had better be a page at pagep!
I also think this would be clearer if written as:
if (PageHWPoison(*pagep)) {
unlock_page(*pagep);
put_page(*pagep);
*pagep = NULL;
return -EIO;
}
return 0;
instead of re-using ret. Sometimes that can make the code flow clearer,
but here, I don't think it does.
> @@ -4168,9 +4201,12 @@ struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
> error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE,
> gfp, NULL, NULL, NULL);
> if (error)
> - page = ERR_PTR(error);
> - else
> - unlock_page(page);
> + return ERR_PTR(error);
> +
> + unlock_page(page);
> + if (PageHWPoison(page))
> + return ERR_PTR(-EIO);
Do we need to put_page() the page in this error case?
next prev parent reply other threads:[~2021-11-14 15:28 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-14 5:32 [UPDATE PATCH] mm: shmem: don't truncate page if memory failure happens Yang Shi
2021-11-14 15:28 ` Matthew Wilcox [this message]
2021-11-14 16:54 ` Yang Shi
2021-11-15 19:00 ` Yang Shi
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