6.12-stable review patch. If anyone has any objections, please let me know.
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From: Andreas Gruenbacher agruenba@redhat.com
[ Upstream commit 2c5f4a53476e3cab70adc77b38942c066bd2c17c ]
Function new_inode() returns a new inode with inode->i_mapping->gfp_mask set to GFP_HIGHUSER_MOVABLE. This value includes the __GFP_FS flag, so allocations in that address space can recurse into filesystem memory reclaim. We don't want that to happen because it can consume a significant amount of stack memory.
Worse than that is that it can also deadlock: for example, in several places, gfs2_unstuff_dinode() is called inside filesystem transactions. This calls filemap_grab_folio(), which can allocate a new folio, which can trigger memory reclaim. If memory reclaim recurses into the filesystem and starts another transaction, a deadlock will ensue.
To fix these kinds of problems, prevent memory reclaim from recursing into filesystem code by making sure that the gfp_mask of inode address spaces doesn't include __GFP_FS.
The "meta" and resource group address spaces were already using GFP_NOFS as their gfp_mask (which doesn't include __GFP_FS). The default value of GFP_HIGHUSER_MOVABLE is less restrictive than GFP_NOFS, though. To avoid being overly limiting, use the default value and only knock off the __GFP_FS flag. I'm not sure if this will actually make a difference, but it also shouldn't hurt.
This patch is loosely based on commit ad22c7a043c2 ("xfs: prevent stack overflows from page cache allocation").
Fixes xfstest generic/273.
Fixes: dc0b9435238c ("gfs: Don't use GFP_NOFS in gfs2_unstuff_dinode") Reviewed-by: Andrew Price anprice@redhat.com Signed-off-by: Andreas Gruenbacher agruenba@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/gfs2/glock.c | 5 ++++- fs/gfs2/inode.c | 15 +++++++++++++++ fs/gfs2/inode.h | 1 + fs/gfs2/ops_fstype.c | 2 +- 4 files changed, 21 insertions(+), 2 deletions(-)
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index e5558e63e2cba..54d0eee24e10b 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -1250,10 +1250,13 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
mapping = gfs2_glock2aspace(gl); if (mapping) { + gfp_t gfp_mask; + mapping->a_ops = &gfs2_meta_aops; mapping->host = sdp->sd_inode; mapping->flags = 0; - mapping_set_gfp_mask(mapping, GFP_NOFS); + gfp_mask = mapping_gfp_mask(sdp->sd_inode->i_mapping); + mapping_set_gfp_mask(mapping, gfp_mask); mapping->i_private_data = NULL; mapping->writeback_index = 0; } diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c index 0b546024f5ef7..90c7a795112d6 100644 --- a/fs/gfs2/inode.c +++ b/fs/gfs2/inode.c @@ -89,6 +89,19 @@ static int iget_set(struct inode *inode, void *opaque) return 0; }
+void gfs2_setup_inode(struct inode *inode) +{ + gfp_t gfp_mask; + + /* + * Ensure all page cache allocations are done from GFP_NOFS context to + * prevent direct reclaim recursion back into the filesystem and blowing + * stacks or deadlocking. + */ + gfp_mask = mapping_gfp_mask(inode->i_mapping); + mapping_set_gfp_mask(inode->i_mapping, gfp_mask & ~__GFP_FS); +} + /** * gfs2_inode_lookup - Lookup an inode * @sb: The super block @@ -132,6 +145,7 @@ struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned int type, struct gfs2_glock *io_gl; int extra_flags = 0;
+ gfs2_setup_inode(inode); error = gfs2_glock_get(sdp, no_addr, &gfs2_inode_glops, CREATE, &ip->i_gl); if (unlikely(error)) @@ -754,6 +768,7 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry, error = -ENOMEM; if (!inode) goto fail_gunlock; + gfs2_setup_inode(inode); ip = GFS2_I(inode);
error = posix_acl_create(dir, &mode, &default_acl, &acl); diff --git a/fs/gfs2/inode.h b/fs/gfs2/inode.h index 225b9d0038cd0..136b231a17f8d 100644 --- a/fs/gfs2/inode.h +++ b/fs/gfs2/inode.h @@ -86,6 +86,7 @@ static inline int gfs2_check_internal_file_size(struct inode *inode, return -EIO; }
+void gfs2_setup_inode(struct inode *inode); struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned type, u64 no_addr, u64 no_formal_ino, unsigned int blktype); diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c index 4a0f7de41b2b2..4c6d1f15a6a84 100644 --- a/fs/gfs2/ops_fstype.c +++ b/fs/gfs2/ops_fstype.c @@ -1185,7 +1185,7 @@ static int gfs2_fill_super(struct super_block *sb, struct fs_context *fc)
mapping = gfs2_aspace(sdp); mapping->a_ops = &gfs2_rgrp_aops; - mapping_set_gfp_mask(mapping, GFP_NOFS); + gfs2_setup_inode(sdp->sd_inode);
error = init_names(sdp, silent); if (error)