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dax: Fix sleep in atomic contex in grab_mapping_entry()
Commit642261ac99
: "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:642261ac99
Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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parent
73b92a2a5e
commit
0cb80b4847
15
fs/dax.c
15
fs/dax.c
@ -333,14 +333,6 @@ restart:
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}
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spin_unlock_irq(&mapping->tree_lock);
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err = radix_tree_preload(
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mapping_gfp_mask(mapping) & ~__GFP_HIGHMEM);
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if (err) {
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if (pmd_downgrade)
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put_locked_mapping_entry(mapping, index, entry);
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return ERR_PTR(err);
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}
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/*
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* Besides huge zero pages the only other thing that gets
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* downgraded are empty entries which don't need to be
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@ -350,6 +342,13 @@ restart:
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unmap_mapping_range(mapping,
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(index << PAGE_SHIFT) & PMD_MASK, PMD_SIZE, 0);
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err = radix_tree_preload(
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mapping_gfp_mask(mapping) & ~__GFP_HIGHMEM);
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if (err) {
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if (pmd_downgrade)
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put_locked_mapping_entry(mapping, index, entry);
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return ERR_PTR(err);
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}
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spin_lock_irq(&mapping->tree_lock);
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if (pmd_downgrade) {
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