Re: [PATCH] mm: PageLRU can be non-atomic bit operation

Hisashi Hifumi
2007-04-23T12:34:37Z

>No. The PG_lru flag bit is just one bit amongst many others:
>what of concurrent operations changing other bits in that same
>unsigned long e.g. trying to lock the page by setting PG_locked?
>There are some places where such micro-optimizations can be made
>(typically while first allocating the page); but in general, no.

In i386 and x86_64, btsl is used to change page flag. In this case, if btsl
without lock prefix
set PG_locked and PG_lru flag concurrently, does only one operation
succeed ?