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From: Baoquan He To: Chris Li Cc: akpm@linux-foundation.org, linux-mm@kvack.org, usama.arif@linux.dev, baohua@kernel.org, kasong@tencent.com, nphamcs@gmail.com, shikemeng@huaweicloud.com, youngjun.park@lge.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 2/3] mm/swap: use swap_ops to register swap device's methods Message-ID: References: <20260417033951.1111038-1-baoquan.he@linux.dev> <20260417033951.1111038-3-baoquan.he@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: BB8BF40005 X-Rspamd-Server: rspam12 X-Stat-Signature: jx1n35bfehh4itmyojny5fhukbsimkj8 X-Rspam-User: X-HE-Tag: 1777006059-357457 X-HE-Meta: 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 iLNhr3EE HWq5yAb38BFfpr7/wiOlqWC2MEgoxmtd4JykTk9sdi8Xjqb4XMdInYYPiJHk5k3ldRUPYdIjXZ+GD9aR2ujZszi3Nrsg+ODdt1f4o/7oP0aOtaLvSzlhWDu0e1kVS3qtAm+Wl6LkHgUcSO4Z0L7o9fQ4takGIZINDJK3audcODwFZCCw8yvwP3g1n7/REy355p0+H7VPH7hxAVsPX9ZkKZf0zi6WOLbyzMxRB/J0aenzI8zRKtyDJkbcJL1JqszfLmPzJtU4mxG2/5GrJZgR7mGLSRUxtmKbfn9uNyz6jPRnzNYJPpeUTDvMMOYWTfyQdZVKZ Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 04/23/26 at 02:48pm, Chris Li wrote: > The incremental change code logic looks fine. > > On Wed, Apr 22, 2026 at 7:37 PM Baoquan He wrote: > > > > diff --git a/mm/swapfile.c b/mm/swapfile.c > > index af81fa212f1e..7644049a0919 100644 > > --- a/mm/swapfile.c > > +++ b/mm/swapfile.c > > @@ -3518,10 +3518,8 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) > > goto bad_swap_unlock_inode; > > } > > > > - if (init_swap_ops(si)) { > > - error = -EINVAL; > > + if (error = init_swap_ops(si)) > > Some more nitpicks: > > I think some compiler option might warn about assigning a variable > inside an if condition. I suggest moving the assignment outside of the > if condition expression. As it is, it looks very close to "error == > init_swap_ops(si))", Some compiler might warn, "Is that what you mean > instead?" I personally prefer the one doing assignment inside if condition expression because it is a ittle neater with one less line. While it doesn't matter much. Here comes the new version of the incremental update. Thanks. diff --git a/mm/swap_io.c b/mm/swap_io.c index 77aa8373c087..e2710d5fb44e 100644 --- a/mm/swap_io.c +++ b/mm/swap_io.c @@ -625,7 +625,7 @@ int init_swap_ops(struct swap_info_struct *sis) sis->ops = &bdev_async_swap_ops; if (!sis->ops || !sis->ops->read_folio || !sis->ops->write_folio) - return -1; + return -EINVAL; return 0; } diff --git a/mm/swapfile.c b/mm/swapfile.c index af81fa212f1e..82d2c9b35b11 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -3518,10 +3518,9 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) goto bad_swap_unlock_inode; } - if (init_swap_ops(si)) { - error = -EINVAL; + error = init_swap_ops(si); + if (error) goto bad_swap_unlock_inode; - } si->max = maxpages; si->pages = maxpages - 1;