* Jaeseon Sim <jason.sim@xxxxxxxxxxx> [230907 00:41]: > > On Thu, Sep 07, 2023 at 12:02:02PM +0800, Peng Zhang wrote: > > > > > > > > > 在 2023/9/7 11:49, Matthew Wilcox 写道: > > > > On Thu, Sep 07, 2023 at 12:39:14PM +0900, 심재선 wrote: > > > > > Use GFP_KERNEL on mas_node_count instead of GFP_NOWAIT | __GFP_NOWARN > > > > > in order to allow memory reclaim. > > > There are many paths that call maple tree's mas_node_count(). Some paths > > > cannot reclaim memory. > > > > Right ... but we should be handling the ENOMEM inside the maple tree and > > allocating some nodes with GFP_KERNEL instead of failing fork(). > > > > > > What testing did you do of this patch? In particular, did you try it > > > > with lockdep enabled? > I did power on/off test with this patch. > I did not try it with lockdep enabled. To accomplish the same result, but with a much smaller scope that will work with lockdep, I would suggest changing mas_expected_entries() to use mas_node_count_gfp() (which already exists) and pass in GFP_KERNEL. Since fork is the only current user of mas_expected_entries(), this won't break other users and we can deal with changing it for others if it is needed. If we do go this route, please add a note in the documentation about using GFP_KERNEL. Willy, does that work for you? Thanks, Liam
