On 09/15, Jerome Marchand wrote: > > On 09/15/2014 06:21 PM, Oleg Nesterov wrote: > > Hi Jerome, > > > > Not sure I understand this patch correctly, will try to read it later. > > But a couple of nits/questions anyway, > > > > On 09/15, Jerome Marchand wrote: > >> > >> +The ShmXXX lines only appears for shmem mapping. They show the amount of memory > >> +from the mapping that is currently: > >> + - resident in RAM but not mapped into any process (ShmNotMapped) > > > > But how can we know that it is not mapped by another process? > > Its mapcount is zero. Ah, yes, I missed the "!count" check. Thanks! > > And in fact "not mapped" looks confusing (at least to me). > > "Not mapped" as "not present in a page table". It does belong to a > userspace mapping though. I wonder if there is a less ambiguous terminology. To me "not present in page tables" looks more understandable, but I won't insist. > > IIUC it is actually > > mapped even by this process, just it never tried to fault these (resident or > > swapped) pages in. Right? > > No these pages are in the page cache. This can happen when the only > process which have accessed these exits or munmap() the mapping. Yes, yes, I meant that this process didn't touch these pages and thus pte_none() == T. > > And I am not sure why we ignore SHMEM_SWAPCACHE... > > Hugh didn't like it as it is a small and transient value. OK, but perhaps update_shmem_stats() should treat it as SHMEM_SWAP. Nevermind, I leave this to you and Hugh. Oleg. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>