On Sun, 2020-12-20 at 02:23 +0100, Mike Galbraith wrote: > On Sun, 2020-12-20 at 02:22 +0200, Vitaly Wool wrote: > > zsmalloc takes bit spinlock in its _map() callback and releases it > > only in unmap() which is unsafe and leads to zswap complaining > > about scheduling in atomic context. > > > > To fix that and to improve RT properties of zsmalloc, remove that > > bit spinlock completely and use a bit flag instead. > > It also does get_cpu_var() in map(), put_cpu_var() in unmap(). That aside, the bit spinlock removal seems to hold up to beating in RT. I stripped out the RT changes to replace the bit spinlocks, applied the still needed atm might_sleep() fix, and ltp zram and zswap test are running in a loop with no signs that it's a bad idea, so I hope that makes it in (minus the preempt disabled spin which I whacked), as it makes zsmalloc markedly more RT friendly. RT changes go from: 1 file changed, 79 insertions(+), 6 deletions(-) to: 1 file changed, 8 insertions(+), 3 deletions(-) -Mike
