On Tue, Feb 07, 2023 at 03:52:53AM +0000, Matthew Wilcox wrote: > On Mon, Feb 06, 2023 at 06:52:58PM -0800, Luis Chamberlain wrote: > > shmem_writepage() sets up variables typically used *after* a possible > > huge page split. However even if that does happen the address space > > mapping should not change. So it should be safe to set that from > > the beginning. > > Yes, we can get mapping from the folio early. It doesn't change > on split. Great. > > The folio should always be locked from the start as well. It however > > was not clear if the folio address can / should change, as well as > > the first inode. > > > > This commit makes no functional changes other a double check on the > > folio locking which might be superflous. This change should help make > > the subsequent patch easier to review. > > You don't need to check that the folio's locked, That BUG_ON() has been on shmem since linux-history days it's probably best as a separate patch. > and you don't > need to reassign inode after the split. Great! Thanks for this confirmation! Luis
