Messages in this thread | | | Date | Wed, 15 Apr 2020 09:02:28 +0200 | From | Michal Hocko <> | Subject | implicit AOP_FLAG_NOFS for grab_cache_page_write_begin |
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Hi, I have just received a bug report about memcg OOM [1]. The underlying issue is memcg specific but the stack trace made me look at the write(2) patch and I have noticed that iomap_write_begin enforces AOP_FLAG_NOFS which means that all the page cache that has to be allocated is GFP_NOFS. What is the reason for this? Do all filesystems really need the reclaim protection? I was hoping that those filesystems which really need NOFS context would be using the scope API (memalloc_nofs_{save,restore}.
Could you clarify please?
[1] http://lkml.kernel.org/r/20200414212558.58eaab4de2ecf864eaa87e5d@linux-foundation.org -- Michal Hocko SUSE Labs
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