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authorJan Kara <jack@suse.cz>2016-12-12 21:34:12 -0500
committerTheodore Ts'o <tytso@mit.edu>2016-12-12 21:34:12 -0500
commit0cb80b4847553582830a59da2c022c37a1f4a119 (patch)
treee16efd7948740c035aef5fad3af596089e6e03da /fs/dax.c
parent73b92a2a5e97d17cc4d5c4fe9d724d3273fb6fd2 (diff)
downloadlinux-0cb80b4847553582830a59da2c022c37a1f4a119.tar.bz2
dax: Fix sleep in atomic contex in grab_mapping_entry()
Commit 642261ac995e: "dax: add struct iomap based DAX PMD support" has introduced unmapping of page tables if huge page needs to be split in grab_mapping_entry(). However the unmapping happens after radix_tree_preload() call which disables preemption and thus unmap_mapping_range() tries to acquire i_mmap_lock in atomic context which is a bug. Fix the problem by moving unmapping before radix_tree_preload() call. Fixes: 642261ac995e01d7837db1f4b90181496f7e6835 Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/dax.c')
-rw-r--r--fs/dax.c15
1 files changed, 7 insertions, 8 deletions
diff --git a/fs/dax.c b/fs/dax.c
index ad131cd2605d..5bfd27b4a69c 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -333,14 +333,6 @@ restart:
}
spin_unlock_irq(&mapping->tree_lock);
- err = radix_tree_preload(
- mapping_gfp_mask(mapping) & ~__GFP_HIGHMEM);
- if (err) {
- if (pmd_downgrade)
- put_locked_mapping_entry(mapping, index, entry);
- return ERR_PTR(err);
- }
-
/*
* Besides huge zero pages the only other thing that gets
* downgraded are empty entries which don't need to be
@@ -350,6 +342,13 @@ restart:
unmap_mapping_range(mapping,
(index << PAGE_SHIFT) & PMD_MASK, PMD_SIZE, 0);
+ err = radix_tree_preload(
+ mapping_gfp_mask(mapping) & ~__GFP_HIGHMEM);
+ if (err) {
+ if (pmd_downgrade)
+ put_locked_mapping_entry(mapping, index, entry);
+ return ERR_PTR(err);
+ }
spin_lock_irq(&mapping->tree_lock);
if (pmd_downgrade) {