linux-kernel - Re: [PATCH v2] fs/ceph/file: fix memory leaks in __ceph_sync

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Message-ID: <CAO8a2Si+7uFkOCf4JxCSkLtJR=_nQOYPAZ_WkWES97ifhyHvBQ@mail.gmail.com>
Date: Thu, 5 Dec 2024 18:30:44 +0200
From: Alex Markuze <amarkuze@...hat.com>
To: Max Kellermann <max.kellermann@...os.com>
Cc: xiubli@...hat.com, idryomov@...il.com, ceph-devel@...r.kernel.org, 
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v2] fs/ceph/file: fix memory leaks in __ceph_sync_read()

Good.
This sequence has not been tested independently, but it should be fine.

On Thu, Dec 5, 2024 at 5:49 PM Max Kellermann <max.kellermann@...os.com> wrote:
>
> In two `break` statements, the call to ceph_release_page_vector() was
> missing, leaking the allocation from ceph_alloc_page_vector().
>
> Instead of adding the missing ceph_release_page_vector() calls, the
> Ceph maintainers preferred to transfer page ownership to the
> `ceph_osd_request` by passing `own_pages=true` to
> osd_req_op_extent_osd_data_pages().  This requires postponing the
> ceph_osdc_put_request() call until after the block that accesses the
> `pages`.
>
> Cc: stable@...r.kernel.org
> Signed-off-by: Max Kellermann <max.kellermann@...os.com>
> ---
>  fs/ceph/file.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
> index 4b8d59ebda00..ce342a5d4b8b 100644
> --- a/fs/ceph/file.c
> +++ b/fs/ceph/file.c
> @@ -1127,7 +1127,7 @@ ssize_t __ceph_sync_read(struct inode *inode, loff_t *ki_pos,
>
>                 osd_req_op_extent_osd_data_pages(req, 0, pages, read_len,
>                                                  offset_in_page(read_off),
> -                                                false, false);
> +                                                false, true);
>
>                 op = &req->r_ops[0];
>                 if (sparse) {
> @@ -1186,8 +1186,6 @@ ssize_t __ceph_sync_read(struct inode *inode, loff_t *ki_pos,
>                         ret = min_t(ssize_t, fret, len);
>                 }
>
> -               ceph_osdc_put_request(req);
> -
>                 /* Short read but not EOF? Zero out the remainder. */
>                 if (ret >= 0 && ret < len && (off + ret < i_size)) {
>                         int zlen = min(len - ret, i_size - off - ret);
> @@ -1221,7 +1219,8 @@ ssize_t __ceph_sync_read(struct inode *inode, loff_t *ki_pos,
>                                 break;
>                         }
>                 }
> -               ceph_release_page_vector(pages, num_pages);
> +
> +               ceph_osdc_put_request(req);
>
>                 if (ret < 0) {
>                         if (ret == -EBLOCKLISTED)
> --
> 2.45.2
>