On pon, 2013-10-07 at 15:03 -0700, Andrew Morton wrote: > On Mon, 07 Oct 2013 17:25:41 +0200 Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx> wrote: > > > During swapoff the frontswap_map was NULL-ified before calling > > frontswap_invalidate_area(). However the frontswap_invalidate_area() > > exits early if frontswap_map is NULL. Invalidate was never called during > > swapoff. > > > > This patch moves frontswap_map_set() in swapoff just after calling > > frontswap_invalidate_area() so outside of locks > > (swap_lock and swap_info_struct->lock). This shouldn't be a problem as > > during swapon the frontswap_map_set() is called also outside of any > > locks. > > > > Ahem. So there's a bunch of code in __frontswap_invalidate_area() > which hasn't ever been executed and nobody noticed it. So perhaps that > code isn't actually needed? > > More seriously, this patch looks like it enables code which hasn't been > used or tested before. How well tested was this? > > Are there any runtime-visible effects from this change? I tested zswap on x86 and x86-64 and there was no difference. This is good as there shouldn't be visible anything because swapoff is unusing all pages anyway: try_to_unuse(type, false, 0); /* force all pages to be unused */ I haven't tested other frontswap users. Best regards, Krzysztof Kozlowski -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>