On Mon, Jun 11, 2018 at 11:44:05AM -0700, Linus Torvalds wrote: > On Mon, Jun 11, 2018 at 11:32 AM Linus Torvalds > <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > > > So now we apparently do a GFP_KERNEL allocation insider the mm zone > > lock, which is broken on just _so_ many levels. > > Oh, I see the comment about how it doesn't actually do an allocation > at all because it's a single-entry. > > Still too damn ugly to live, and much too fragile. No way in hell do > we even _hint_ at a GFP_KERNEL when we're inside a context that can't > do any memory allocation at all. > > Plus I'm not convinced it's a "no allocation" path even despite that > comment, because it also does a "dma_map_page()" etc, which can cause > allocations to do the dma mapping thing afaik. No? Well no because DMA is triggered by the IOMMU flag and that is always off for the balloon. But I hear what you are saying about it being fragile. > Maybe there's some reason why that doesn't happen either, but > basically this whole callchain looks *way* to complicated to be used > under a core VM spinlock. > > Linus Maybe it will help to have GFP_NONE which will make any allocation fail if attempted. Linus, would this address your comment? -- MST _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
