On Thu 15-12-16 13:50:59, Dave Jiang wrote: > The caller into dax needs to clear __GFP_FS mask bit since it's > responsible for acquiring locks / transactions that blocks __GFP_FS > allocation. The caller will restore the original mask when dax function > returns. Could you have a look at [1]. Does the new API look like a fit for your use case here? It at least sounds a bit easier from the code POV to me. [1] http://lkml.kernel.org/r/20161215140715.12732-1-mhocko@xxxxxxxxxx > > Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx> > Reviewed-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> > Reviewed-by: Jan Kara <jack@xxxxxxx> > --- > fs/dax.c | 1 + > fs/ext2/file.c | 9 ++++++++- > fs/ext4/file.c | 10 +++++++++- > fs/xfs/xfs_file.c | 14 +++++++++++++- > 4 files changed, 31 insertions(+), 3 deletions(-) > > diff --git a/fs/dax.c b/fs/dax.c > index d3fe880..6395bc6 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -1380,6 +1380,7 @@ int dax_iomap_pmd_fault(struct vm_area_struct *vma, unsigned long address, > vmf.pgoff = pgoff; > vmf.flags = flags; > vmf.gfp_mask = mapping_gfp_mask(mapping) | __GFP_IO; > + vmf.gfp_mask &= ~__GFP_FS; > > switch (iomap.type) { > case IOMAP_MAPPED: > diff --git a/fs/ext2/file.c b/fs/ext2/file.c > index b0f2415..8422d5f 100644 > --- a/fs/ext2/file.c > +++ b/fs/ext2/file.c > @@ -92,16 +92,19 @@ static int ext2_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf) > struct inode *inode = file_inode(vma->vm_file); > struct ext2_inode_info *ei = EXT2_I(inode); > int ret; > + gfp_t old_gfp = vmf->gfp_mask; > > if (vmf->flags & FAULT_FLAG_WRITE) { > sb_start_pagefault(inode->i_sb); > file_update_time(vma->vm_file); > } > + vmf->gfp_mask &= ~__GFP_FS; > down_read(&ei->dax_sem); > > ret = dax_iomap_fault(vma, vmf, &ext2_iomap_ops); > > up_read(&ei->dax_sem); > + vmf->gfp_mask = old_gfp; > if (vmf->flags & FAULT_FLAG_WRITE) > sb_end_pagefault(inode->i_sb); > return ret; > @@ -114,6 +117,7 @@ static int ext2_dax_pfn_mkwrite(struct vm_area_struct *vma, > struct ext2_inode_info *ei = EXT2_I(inode); > loff_t size; > int ret; > + gfp_t old_gfp = vmf->gfp_mask; > > sb_start_pagefault(inode->i_sb); > file_update_time(vma->vm_file); > @@ -123,8 +127,11 @@ static int ext2_dax_pfn_mkwrite(struct vm_area_struct *vma, > size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; > if (vmf->pgoff >= size) > ret = VM_FAULT_SIGBUS; > - else > + else { > + vmf->gfp_mask &= ~__GFP_FS; > ret = dax_pfn_mkwrite(vma, vmf); > + vmf->gfp_mask = old_gfp; > + } > > up_read(&ei->dax_sem); > sb_end_pagefault(inode->i_sb); > diff --git a/fs/ext4/file.c b/fs/ext4/file.c > index d663d3d..a3f2bf0 100644 > --- a/fs/ext4/file.c > +++ b/fs/ext4/file.c > @@ -261,14 +261,17 @@ static int ext4_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf) > struct inode *inode = file_inode(vma->vm_file); > struct super_block *sb = inode->i_sb; > bool write = vmf->flags & FAULT_FLAG_WRITE; > + gfp_t old_gfp = vmf->gfp_mask; > > if (write) { > sb_start_pagefault(sb); > file_update_time(vma->vm_file); > } > + vmf->gfp_mask &= ~__GFP_FS; > down_read(&EXT4_I(inode)->i_mmap_sem); > result = dax_iomap_fault(vma, vmf, &ext4_iomap_ops); > up_read(&EXT4_I(inode)->i_mmap_sem); > + vmf->gfp_mask = old_gfp; > if (write) > sb_end_pagefault(sb); > > @@ -320,8 +323,13 @@ static int ext4_dax_pfn_mkwrite(struct vm_area_struct *vma, > size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; > if (vmf->pgoff >= size) > ret = VM_FAULT_SIGBUS; > - else > + else { > + gfp_t old_gfp = vmf->gfp_mask; > + > + vmf->gfp_mask &= ~__GFP_FS; > ret = dax_pfn_mkwrite(vma, vmf); > + vmf->gfp_mask = old_gfp; > + } > up_read(&EXT4_I(inode)->i_mmap_sem); > sb_end_pagefault(sb); > > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c > index d818c16..52202b4 100644 > --- a/fs/xfs/xfs_file.c > +++ b/fs/xfs/xfs_file.c > @@ -1474,7 +1474,11 @@ xfs_filemap_page_mkwrite( > xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED); > > if (IS_DAX(inode)) { > + gfp_t old_gfp = vmf->gfp_mask; > + > + vmf->gfp_mask &= ~__GFP_FS; > ret = dax_iomap_fault(vma, vmf, &xfs_iomap_ops); > + vmf->gfp_mask = old_gfp; > } else { > ret = iomap_page_mkwrite(vma, vmf, &xfs_iomap_ops); > ret = block_page_mkwrite_return(ret); > @@ -1502,13 +1506,16 @@ xfs_filemap_fault( > > xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED); > if (IS_DAX(inode)) { > + gfp_t old_gfp = vmf->gfp_mask; > /* > * we do not want to trigger unwritten extent conversion on read > * faults - that is unnecessary overhead and would also require > * changes to xfs_get_blocks_direct() to map unwritten extent > * ioend for conversion on read-only mappings. > */ > + vmf->gfp_mask &= ~__GFP_FS; > ret = dax_iomap_fault(vma, vmf, &xfs_iomap_ops); > + vmf->gfp_mask = old_gfp; > } else > ret = filemap_fault(vma, vmf); > xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED); > @@ -1581,8 +1588,13 @@ xfs_filemap_pfn_mkwrite( > size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; > if (vmf->pgoff >= size) > ret = VM_FAULT_SIGBUS; > - else if (IS_DAX(inode)) > + else if (IS_DAX(inode)) { > + gfp_t old_gfp = vmf->gfp_mask; > + > + vmf->gfp_mask &= ~__GFP_FS; > ret = dax_pfn_mkwrite(vma, vmf); > + vmf->gfp_mask = old_gfp; > + } > xfs_iunlock(ip, XFS_MMAPLOCK_SHARED); > sb_end_pagefault(inode->i_sb); > return ret; > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@xxxxxxxxx. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>