On 2024/2/28 13:29, Sergey Senozhatsky wrote: > On (24/02/28 13:14), Chengming Zhou wrote: >> On 2024/2/28 12:33, Sergey Senozhatsky wrote: >>> On (24/02/27 03:02), Chengming Zhou wrote: >>> [..] >>>> @@ -978,10 +974,11 @@ static struct zspage *alloc_zspage(struct zs_pool *pool, >>>> pages[i] = page; >>>> } >>>> >>>> - create_page_chain(class, zspage, pages); >>>> init_zspage(class, zspage); >>>> zspage->pool = pool; >>>> zspage->class = class->index; >>>> + /* RCU set_zspage() after zspage initialized. */ >>>> + create_page_chain(class, zspage, pages); >>> >>> So this hasn't been tested, has it? >> I have tested it in my test vm, but it hasn't KASAN enabled. I tested the >> kernel build in tmpfs with zswap enabled using zsmalloc pool, not sure >> why the kernel didn't crash then... > > I hit the problem on non-kasan-enabled kernel. KASAN was enabled > later on. Ok, It should be a problem with my process, sorry. > > [..] > >>> So when init_zspage() calls get_first_page() it gets NULL zspage->first_page >>> which we then use in is_first_page(first_page)->PagePrivate(page). As far as >>> I can tell. >> >> Thanks! I will fix it and test throughly before send an update. > > I'm curious if we want to add RCU to the picture, given that zsmalloc > is quite often run under memory pressure. Yes, it's a reasonable point. But given struct zspage size has only 56 bytes, it maybe not a problem to delay its free to RCU? Thanks.
