On Thu, Jan 18, 2024 at 12:14 PM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: > > On Thu, Jan 18, 2024 at 05:35:04AM -0800, Yang Shi wrote: > > It doesn't make too much sense to force huge page alignment on 32 bit > > system due to the constrained virtual address space. > > > > [1] https://lore.kernel.org/linux-mm/CAHbLzkqa1SCBA10yjWTtA2mKCsoK5+M1BthSDL8ROvUq2XxZMw@xxxxxxxxxxxxxx/T/#mf211643a0427f8d6495b5b53f8132f453d60ab95 > > [2] https://lore.kernel.org/linux-mm/CAHbLzkqa1SCBA10yjWTtA2mKCsoK5+M1BthSDL8ROvUq2XxZMw@xxxxxxxxxxxxxx/T/#me93dff2ccbd9902c3e395e1c022fb454e48ecb1d > > I feel sure there are shorter URLs for those messages ... Oh, yeah, I just found. [1] https://lore.kernel.org/linux-mm/d0a136a0-4a31-46bc-adf4-2db109a61672@xxxxxxxxxx/ [2] https://lore.kernel.org/linux-mm/CAJuCfpHXLdQy1a2B6xN2d7quTYwg2OoZseYPZTRpU0eHHKD-sQ@xxxxxxxxxxxxxx/ > > > @@ -811,6 +812,14 @@ static unsigned long __thp_get_unmapped_area(struct file *filp, > > loff_t off_align = round_up(off, size); > > unsigned long len_pad, ret; > > > > + /* > > + * It doesn't make too much sense to froce huge page alignment on > > + * 32 bit system or compat userspace due to the contrained virtual > > + * address space and address entropy. > > + */ > > I honestly wouldn't even comment this. But if you must, > > /* Using THP alignment is not as important as address randomisation */ It is not only about address randomization. Removing the comment is fine too. > > > + if (IS_ENABLED(CONFIG_32BIT) || in_compat_syscall()) > > + return 0; > > + > > if (off_end <= off_align || (off_end - off_align) < size) > > return 0; > > > > -- > > 2.41.0 > >
