On Mon, Oct 23, 2023 at 08:10:32PM +0200, domenico cerasuolo wrote: > Il giorno lun 23 ott 2023 alle ore 19:53 Andrew Morton > <akpm@xxxxxxxxxxxxxxxxxxxx> ha scritto: > > > > On Mon, 23 Oct 2023 18:53:26 +0200 domenico cerasuolo <mimmocerasuolo@xxxxxxxxx> wrote: > > > > > > Rebased to mm.git's current mm-stable, to resolve with removal of > > > > vma_policy() from include/linux/mempolicy.h, and temporary omission > > > > of Nhat's ZSWAP mods from mm/swap_state.c: no other changes. > > > > > > Hi Hugh, > > > > > > not sure if it's the rebase, but I don't see an update to > > > __read_swap_cache_async invocation in zswap.c at line 1078. Shouldn't we pass a > > > mempolicy there too? > > > > No change needed. zswap_writeback_entry() was passing a NULL for arg > > `vma' and it's now passing a NULL for arg `mpol'. > > Problem is that alloc_pages_mpol is dereferencing mpol, when I test the zswap > writeback at 397148729f21edcf700ecb2a01749dbce955d09e it crashes, not sure if > I'm missing something. I don't think you are. The NULL vma used to go to get_vma_policy(), which fell back to pol = get_task_policy(current); Now the NULL pol gets passed to alloc_pages_mpol() directly, which dereferences it. Oops. I think Hugh's patch needs zswap to pass get_task_policy(current) instead of NULL.
