RFC This is Part II of the series [1] that makes zram read() and write() preemptible. This part focuses only zsmalloc because zsmalloc imposes atomicity restrictions on its users. One notable example is object mapping API, which returns with: a) local CPU lock held b) zspage rwlock held First, zsmalloc is converted to use sleepable locks for internal structs/data managements. Second, a new handle mapping is introduced (temporarily, until we remove zs_map_object/zs_unmap_object) which doesn't use per-CPU buffers (and hence local CPU lock) but requires users to provide a pointer to temp buffer for objects copy-in (when needed) so the callers now should be able to schedule while having objects mapped. The series makes zsmalloc preemptible which, in turn, makes zram read() preemptible. [1] https://lore.kernel.org/linux-mm/20250127072932.1289973-1-senozhatsky@xxxxxxxxxxxx Sergey Senozhatsky (6): zram: deffer slot free notification zsmalloc: make zspage lock preemptible zsmalloc: convert to sleepable pool lock zsmalloc: make class lock sleepable zsmalloc: introduce handle mapping API zram: switch over to zshandle mapping API drivers/block/zram/zcomp.c | 4 +- drivers/block/zram/zcomp.h | 2 + drivers/block/zram/zram_drv.c | 169 ++++++++++----- drivers/block/zram/zram_drv.h | 4 + include/linux/zsmalloc.h | 29 +++ mm/zsmalloc.c | 372 ++++++++++++++++++++++------------ 6 files changed, 404 insertions(+), 176 deletions(-) -- 2.48.1.262.g85cc9f2d1e-goog
