From: Vlastimil Babka <vbabka@suse.cz>
To: Michal Hocko <mhocko@kernel.org>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
Dave Chinner <david@fromorbit.com>,
djwong@kernel.org, "Theodore Ts'o" <tytso@mit.edu>,
Chris Mason <clm@fb.com>, David Sterba <dsterba@suse.cz>,
Jan Kara <jack@suse.cz>,
ceph-devel@vger.kernel.org, cluster-devel@redhat.com,
linux-nfs@vger.kernel.org, logfs@logfs.org,
linux-xfs@vger.kernel.org, linux-ext4@vger.kernel.org,
linux-btrfs@vger.kernel.org, linux-mtd@lists.infradead.org,
reiserfs-devel@vger.kernel.org,
linux-ntfs-dev@lists.sourceforge.net,
linux-f2fs-devel@lists.sourceforge.net,
linux-afs@lists.infradead.org,
LKML <linux-kernel@vger.kernel.org>,
Michal Hocko <mhocko@suse.com>
Subject: Re: [PATCH 4/8] xfs: use memalloc_nofs_{save,restore} instead of memalloc_noio*
Date: Mon, 9 Jan 2017 15:08:27 +0100 [thread overview]
Message-ID: <18f9363f-144d-0bfd-5116-08d5f4648869@suse.cz> (raw)
In-Reply-To: <20170106141107.23953-5-mhocko@kernel.org>
On 01/06/2017 03:11 PM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
>
> kmem_zalloc_large and _xfs_buf_map_pages use memalloc_noio_{save,restore}
> API to prevent from reclaim recursion into the fs because vmalloc can
> invoke unconditional GFP_KERNEL allocations and these functions might be
> called from the NOFS contexts. The memalloc_noio_save will enforce
> GFP_NOIO context which is even weaker than GFP_NOFS and that seems to be
> unnecessary. Let's use memalloc_nofs_{save,restore} instead as it should
> provide exactly what we need here - implicit GFP_NOFS context.
>
> Changes since v1
> - s@memalloc_noio_restore@memalloc_nofs_restore@ in _xfs_buf_map_pages
> as per Brian Foster
>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
Not a xfs expert, but seems correct.
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Nit below:
> ---
> fs/xfs/kmem.c | 10 +++++-----
> fs/xfs/xfs_buf.c | 8 ++++----
> 2 files changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/fs/xfs/kmem.c b/fs/xfs/kmem.c
> index a76a05dae96b..d69ed5e76621 100644
> --- a/fs/xfs/kmem.c
> +++ b/fs/xfs/kmem.c
> @@ -65,7 +65,7 @@ kmem_alloc(size_t size, xfs_km_flags_t flags)
> void *
> kmem_zalloc_large(size_t size, xfs_km_flags_t flags)
> {
> - unsigned noio_flag = 0;
> + unsigned nofs_flag = 0;
> void *ptr;
> gfp_t lflags;
>
> @@ -80,14 +80,14 @@ kmem_zalloc_large(size_t size, xfs_km_flags_t flags)
> * context via PF_MEMALLOC_NOIO to prevent memory reclaim re-entering
> * the filesystem here and potentially deadlocking.
The comment above is now largely obsolete, or minimally should be
changed to PF_MEMALLOC_NOFS?
> */
> - if ((current->flags & PF_MEMALLOC_NOFS) || (flags & KM_NOFS))
> - noio_flag = memalloc_noio_save();
> + if (flags & KM_NOFS)
> + nofs_flag = memalloc_nofs_save();
>
> lflags = kmem_flags_convert(flags);
> ptr = __vmalloc(size, lflags | __GFP_HIGHMEM | __GFP_ZERO, PAGE_KERNEL);
>
> - if ((current->flags & PF_MEMALLOC_NOFS) || (flags & KM_NOFS))
> - memalloc_noio_restore(noio_flag);
> + if (flags & KM_NOFS)
> + memalloc_nofs_restore(nofs_flag);
>
> return ptr;
> }
> diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
> index 7f0a01f7b592..8cb8dd4cdfd8 100644
> --- a/fs/xfs/xfs_buf.c
> +++ b/fs/xfs/xfs_buf.c
> @@ -441,17 +441,17 @@ _xfs_buf_map_pages(
> bp->b_addr = NULL;
> } else {
> int retried = 0;
> - unsigned noio_flag;
> + unsigned nofs_flag;
>
> /*
> * vm_map_ram() will allocate auxillary structures (e.g.
> * pagetables) with GFP_KERNEL, yet we are likely to be under
> * GFP_NOFS context here. Hence we need to tell memory reclaim
> - * that we are in such a context via PF_MEMALLOC_NOIO to prevent
> + * that we are in such a context via PF_MEMALLOC_NOFS to prevent
> * memory reclaim re-entering the filesystem here and
> * potentially deadlocking.
> */
> - noio_flag = memalloc_noio_save();
> + nofs_flag = memalloc_nofs_save();
> do {
> bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count,
> -1, PAGE_KERNEL);
> @@ -459,7 +459,7 @@ _xfs_buf_map_pages(
> break;
> vm_unmap_aliases();
> } while (retried++ <= 1);
> - memalloc_noio_restore(noio_flag);
> + memalloc_nofs_restore(nofs_flag);
>
> if (!bp->b_addr)
> return -ENOMEM;
>
next prev parent reply other threads:[~2017-01-09 14:09 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-06 14:10 [PATCH 0/8 v3] scope GFP_NOFS api Michal Hocko
2017-01-06 14:11 ` [PATCH 1/8] lockdep: allow to disable reclaim lockup detection Michal Hocko
2017-01-09 12:56 ` Vlastimil Babka
2017-01-06 14:11 ` [PATCH 2/8] xfs: abstract PF_FSTRANS to PF_MEMALLOC_NOFS Michal Hocko
2017-01-09 12:59 ` Vlastimil Babka
2017-01-09 14:29 ` Michal Hocko
2017-01-09 20:58 ` Darrick J. Wong
2017-01-06 14:11 ` [PATCH 3/8] mm: introduce memalloc_nofs_{save,restore} API Michal Hocko
2017-01-09 13:04 ` Vlastimil Babka
2017-01-09 13:42 ` Michal Hocko
2017-01-09 13:59 ` Michal Hocko
2017-01-09 14:04 ` Vlastimil Babka
2017-01-06 14:11 ` [PATCH 4/8] xfs: use memalloc_nofs_{save,restore} instead of memalloc_noio* Michal Hocko
2017-01-09 14:08 ` Vlastimil Babka [this message]
2017-01-09 14:25 ` Michal Hocko
2017-01-09 15:56 ` Brian Foster
2017-01-09 20:59 ` Darrick J. Wong
2017-01-06 14:11 ` [PATCH 5/8] jbd2: mark the transaction context with the scope GFP_NOFS context Michal Hocko
2017-01-06 14:11 ` [PATCH 6/8] jbd2: make the whole kjournald2 kthread NOFS safe Michal Hocko
2017-01-06 14:11 ` [PATCH 7/8] Revert "ext4: avoid deadlocks in the writeback path by using sb_getblk_gfp" Michal Hocko
2017-01-17 3:01 ` Theodore Ts'o
2017-01-17 7:54 ` Michal Hocko
2017-03-06 11:59 ` Michal Hocko
2017-01-06 14:11 ` [PATCH 8/8] Revert "ext4: fix wrong gfp type under transaction" Michal Hocko
2017-01-17 2:56 ` Theodore Ts'o
2017-01-17 8:24 ` Michal Hocko
2017-01-17 15:18 ` Michal Hocko
2017-01-17 15:59 ` Theodore Ts'o
2017-01-17 16:16 ` Michal Hocko
2017-01-17 17:29 ` Jan Kara
2017-01-19 8:39 ` Michal Hocko
2017-01-19 9:22 ` Jan Kara
2017-01-19 9:44 ` Michal Hocko
2017-01-26 7:44 ` Michal Hocko
2017-01-27 6:13 ` Theodore Ts'o
2017-01-27 9:37 ` Michal Hocko
2017-01-27 16:40 ` Theodore Ts'o
2017-01-28 7:32 ` [Cluster-devel] " Christoph Hellwig
2017-01-28 8:17 ` David Lang
2017-01-30 8:12 ` Michal Hocko
2017-02-03 15:32 ` Michal Hocko
2017-01-17 21:04 ` Andreas Dilger
2017-01-18 8:29 ` Michal Hocko
2017-01-06 14:18 ` [DEBUG PATCH 0/2] debug explicit GFP_NO{FS,IO} usage from the scope context Michal Hocko
2017-01-06 14:18 ` [DEBUG PATCH 1/2] mm, debug: report when GFP_NO{FS,IO} is used explicitly from memalloc_no{fs,io}_{save,restore} context Michal Hocko
2017-01-06 14:18 ` [DEBUG PATCH 2/2] silent warnings which we cannot do anything about Michal Hocko
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