Hi, > kmem_cache_zalloc() without __GFP_NOFAIL may fail. > > btrfs use kmem_cache_zalloc() with GFP_NOFS mostly, > and only few place with __GFP_NOFAIL. > > xfs use kmem_cache_zalloc() with __GFP_NOFAIL mostly. > > It is very difficult to test all case of failure in kmem_cache_zalloc() . > > Should btrfs use kmem_cache_zalloc() with __GFP_NOFAIL just like xfs > or use mempool with pre-alloc to prevent fail?
I tried both way. 1) add __GFP_NOFAIL to kmem_cache_zalloc() see 0001-btrfs-add-__GFP_NOFAIL-to-kmem_cache.patch but this problem still happened in test. 2) switch to use mempool_t for btrfs_path see 0001-btrfs-switch-to-mempool_t-for-btrfs_path.patch this problem yet not happen in test. But the memory alloc failure is difficult to test, we need more review. Best Regards Wang Yugui (wangyu...@e16-tech.com) 2021/03/28
0001-btrfs-add-__GFP_NOFAIL-to-kmem_cache.patch
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0001-btrfs-switch-to-mempool_t-for-btrfs_path.patch
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