From: Brian Foster Subject: Re: [PATCH 5/9] xfs: use memalloc_nofs_{save,restore} instead of memalloc_noio* Date: Fri, 16 Dec 2016 11:38:11 -0500 Message-ID: <20161216163811.GG8447@bfoster.bfoster> References: <20161215140715.12732-1-mhocko@kernel.org> <20161215140715.12732-6-mhocko@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Andrew Morton , Dave Chinner , "Theodore Ts'o" , Chris Mason , David Sterba , Jan Kara , 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 , Michal Hocko To: Michal Hocko Return-path: Content-Disposition: inline In-Reply-To: <20161215140715.12732-6-mhocko@kernel.org> Sender: owner-linux-mm@kvack.org List-Id: linux-ext4.vger.kernel.org On Thu, Dec 15, 2016 at 03:07:11PM +0100, Michal Hocko wrote: > From: Michal Hocko > > 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. > > Signed-off-by: Michal Hocko > --- > fs/xfs/kmem.c | 10 +++++----- > fs/xfs/xfs_buf.c | 8 ++++---- > 2 files changed, 9 insertions(+), 9 deletions(-) > ... > diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c > index f31ae592dcae..5c6f9bd4d8be 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_noio_restore(nofs_flag); memalloc_nofs_restore() ? Brian > > if (!bp->b_addr) > return -ENOMEM; > -- > 2.10.2 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org