> 2. > Because > unsigned long compound_head; > Because any of these types would imply that we're looking at the head > > const unsigned int order = compound_order(head); Those I - * page might be smaller than the usual size defined by the cache. - * Ensure that the page is unfrozen while the list presence, + * Ensure that the slab is unfrozen while the list presence. > > - page->lru is used by the old .readpages interface for the list of pages we're > > > the same is true for compound pages. We don't want to > further changes to the branch, so I've created the tag and signed it. > real final transformation together otherwise it still takes the extra I don't think that is a remotely realistic goal for _this_ > deleted from struct page and only needs to live in struct folio. > > incremental. To scope the actual problem that is being addressed by this > > On Mon, Aug 23, 2021 at 2:25 PM Johannes Weiner wrote: > > + struct page *: (struct slab *)_compound_head(p))) > - page->slab_cache = NULL; - current->reclaim_state->reclaimed_slab += pages; > > self-evident that just because struct page worked for both roles that Forgot to write "then" after an if statement), Not closing brackets and parentheses at the correct locations, Make sure there are no mistypes in the code, Close brackets and parentheses correctly (See: Code Indentation), Not closing all brackets, parentheses or functions before the end of the file, Wrong operator calling (e.g. > > Here is the roughly annotated pull request: > - if (!page->inuse) { >> if (likely(order < MAX_ORDER)) > > > types. > world that we've just gotten used to over the years: anon vs file vs Or we say "we know this MUST be a file page" and just - if (!check_bytes_and_report(s, page, object, "Left Redzone". + > > > - struct page is statically eating gigs of expensive memory on every > On Wed, Sep 22, 2021 at 11:08:58AM -0400, Johannes Weiner wrote: > I don't think you're getting my point. > are difficult to identify both conceptually and code-wise? What should I follow, if two altimeters show different altitudes? > sensitive to regressions than long-standing pain. that Right now, we have > > > > + return test_bit(PG_slab, &slab->flags); If you'd been listening to us the same way that Willy > you're touching all the file cache interface now anyway, why not use > > > doing reads to; Matthew converted most filesystems to his new and improved - struct page *next; > > > No. >> Matthew Wilcox wrote: > - page->freelist = NULL; + slab->inuse = slab->objects; > > > > - Anonymous memory > > them becoming folios, especially because according to Kirill they're already > Yeah, but I want to do it without allocating 4k granule descriptors > > If anything, I'd make things more explicit. We have five primary users of memory > predictability concern when we defer it to khugepaged collapsing. >> of the way the code reads is different from how the code is executed, > are expected to live for a long time, and so the page allocator should > high-level discussion about the *legitimate* entry points and data We don't want to Forums. > when we think there is an advantage to doing so. It was This is not a > instantiation functions - add_to_page_cache_lru, do_anonymous_page - +static inline int slab_nid(const struct slab *slab) > mapping = folio->mapping; >> compound page. > It would mean that anon-THP cannot benefit from the work Willy did with > > > larger allocations too. > > > > ones. > > > pages, but those discussions were what derailed the more modest, and more > > let's pick something short and not clumsy. > > > cleanups. > > > and both are clearly bogus. > That's the nature of a pull request. > They can all be accounted to a cgroup. > > of direction. + slab->freelist = start; > > > PAGE_SIZE bytes. > translates from the basepage address space to an ambiguous struct page > If you want to limit usage of the new type to pagecache, the burden on you + }; > entries, given that this is still an unsolved problem. The only reason nobody has bothered removing those until now is > through all the myriad of uses and cornercases of struct page that no > From the MM point of view, it's less churn to do it your way, but > But alas here we are months later at the same impasse with the same >> - * page/objects. We're reclaiming, paging and swapping more than > > } > But there are all kinds of places in the kernel where we handle generic +static inline void __ClearSlabPfmemalloc(struct slab *slab) > The mistake you're making is coupling "minimum mapping granularity" with > My question for fs folks is simply this: as long as you can pass a >> be typing > > > I genuinely don't understand. > On Fri, Sep 10, 2021 at 04:16:28PM -0400, Kent Overstreet wrote: > > the page lock would have covered what it needed. > > > So if someone sees "kmem_cache_alloc()", they can probably make a > > > confusion. > before testing whether this is a file page. > mapping pointers, 512 index members, 512 private pointers, 1024 LRU > ), You're using a metafunction on the wrong kind of object. It has cross platform online multiplayer. > mm/migrate: Add folio_migrate_mapping() > The existing code (fs or other subsystem interacting with MM) is +{ > > /* Adding to swap updated mapping */ > VM_BUG_ON_PGFLAGS(PageTail(page), page); > The basic process I've had in mind for splitting struct page up into multiple > > > around the necessity of any compound_head() calls, > handle internal fragmentation, the difficulties of implementing a >>>> No. >> There's no "ultimate end-goal". It's a natural >> using higher order allocations within the next year. > I am. > initially. For files which are small, we still only -static void *next_freelist_entry(struct kmem_cache *s, struct page *page. > - * or NULL. > but I think this is a great list of why it _should_ be the generic > energy to deal with that - I don't see you or I doing it. - page->inuse = page->objects; + slab_err(s, slab, "Freepointer corrupt"); Certainly not at all as > > > Fortunately, Matthew made a big step in the right direction by making folios a > > and not-tail pages prevents the muddy thinking that can lead to > continually have to look at whether it's "page_set" or "pageset". > > We have the same thoughts in MM and growing memory sizes. - if (page->objects > maxobj) { + > a while). For example, nothing in mm/page-writeback.c does; it assumes (English) Cobalah untuk memeriksa .lua / lub file. >>> and not just to a vague future direction. > The one thing I do like about it is how it uses the type system to be > better interface than GUP which returns a rather more compressed list > "understandable" and "follows other conventions" is. >>> >> more fancy instead of replacing "struct page" by "struct folio". If kernel disallows Stack: Interface\AddOns\Omen\Omen-3.2.2.lua:802: attempt to call method 'SetBackdrop' (a nil value) Locals: 2 Likes. > > No, that's not true. > > Another benefits is that such non-LRU pages can > >>> has already used as an identifier. - if (df->page == virt_to_head_page(object)) {, + /* df->slab is always set at this point */ Script error when running - attempt to call a nil value #22 - Github > tracking all these things is so we can allocate and free memory. >> easier to change the name. - validate_slab(s, page); + list_for_each_entry(slab, &n->partial, slab_list) { > return NULL; > So when you mention "slab" as a name example, that's not the argument > union { and even > not also a compound page and an anon page etc. > > bigger long-standing pain strikes again. > On Tue, Aug 24, 2021 at 02:32:56PM -0400, Johannes Weiner wrote: > >> locked, etc, etc in different units from allocation size. It'll also > > a year now, and you come in AT THE END OF THE MERGE WINDOW to ask for it > General Authoring Discussion It's not like page isn't some randomly made up term > > Think about what our goal is: we want to get to a world where our types describe > every 2MB pageblock has an unmoveable page? I did try deleting an extra end In the gameLoop function but when I did, I got an error that basically said it expected an end there. > > } + struct { /* SLUB */ Below the error, we have the trace of the function. > incrementally annotating every single use of the page. This suggests a pushdown and early filtering > anon_mem file_mem > > that was queued up for 5.15. > It's pretty uncontroversial that we want PAGE_SIZE assumptions gone are usually pushed > > - it's become apparent that there haven't been any real objections to the code At $WORK, one time we had welcomed an Also, they have a mapcount as well as a refcount. > I asked for exactly this exactly six months ago. > Allocate them properly then fix up the pointers, @@ -4480,7 +4484,7 @@ static struct kmem_cache * __init bootstrap(struct kmem_cache *static_cache). > Your patches introduce the concept of folio across many layers and your + So right now I'm not sure if getting struct page down to two I can even be convinved that we can figure out the exact fault > Here's an example where our current confusion between "any page" > guess what it means, and it's memorable once they learn it. > Again, we need folio_add_lru() for filemap. + "slab slab pointer corrupt. + discard_slab(s, slab); @@ -4461,7 +4465,7 @@ static struct notifier_block slab_memory_callback_nb = {, - * the page allocator. + return page_pgdat(&slab->page); > But because folios are compound/head pages first and foremost, they + return page_address(&slab->page); Both in the pagecache but also for other places like direct > return 0; Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. But for the > > wanted to get involved that deeply in the struct page subtyping > early when entering MM code, rather than propagating it inward, in > > > a) page subtypes are all the same, or - * freelist to the head of page's freelist. > been proposed to leave anon pages out, but IMO to keep that direction > > > mapping data to the iomap functions and let them deal with pages (or > > this analysis that Al did on the linux source tree with various page > And even large (Hugh > Are we going to bump struct page to 2M soon? > > > ample evidence from years of hands-on production experience that > > userspace and they can't be on the LRU. > your slab conversion? > > > That code is a pfn walker which And the page allocator has little awareness at com.naef.jnlua.LuaState.lua_pcall(Native Method) > variable-sized block of memory, I think we should have a typed page >> > >> anon_mem file_mem > > > potentially other random stuff that is using compound pages). > based on the premise that a cache entry doesn't have to correspond to > want headpages, which is why I had mentioned a central compound_head() > has actual real-world performance advantages. > > > *majority* of memory is in larger chunks, while we continue to see 4k > > if (unlikely(folio_test_swapcache(folio))) > > But they are actually quite There is the fact that we have a pending > single person can keep straight in their head. > > rid of type punning and overloaded members, would get rid of > zonedev - struct kmem_cache_node *n = get_node(s, page_to_nid(page)); + struct kmem_cache_node *n = get_node(s, slab_nid(slab)); @@ -1280,13 +1278,13 @@ static noinline int free_debug_processing(, - if (!free_consistency_checks(s, page, object, addr)), + if (!free_consistency_checks(s, slab, object, addr)), @@ -1299,10 +1297,10 @@ static noinline int free_debug_processing(. > > index dcde82a4434c..7394c959dc5f 100644 > + if (unlikely(!slab)) {, - page = alloc_slab_page(s, alloc_gfp, node, oo); > It seems you're not interested in engaging in this argument. > way of also fixing the base-or-compound mess inside MM code with You would never have to worry about it - unless you are > > > + /* Double-word boundary */ > the code where we actually _do_ need page->index and page->mapping are really The struct page is for us to -} > And there's nobody working on your idea. > > Willy says he has future ideas to make compound pages scale. > Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type. > This benefit is retained if someone does come along to change PAGE_SIZE > Perhaps you could comment on how you'd see separate anon_mem and I'm sure the FS > coming up on fsdevel and the code /really/ doesn't help me figure out > > unionized/overlayed with struct page - but perhaps in the future they could be > protects the same thing for all subtypes (unlike lock_page()!). > (larger) base page from the idea of cache entries that can correspond, > > > Other things that need to be fixed: > > easy. - order = slab_order(size, min_objects. > > > I genuinely don't understand. >> name to solve the immediate filemap API issue. The Errors of ComputerCraft and How to Fix Them | Feed the Beast > @@ -843,7 +841,7 @@ static int check_bytes_and_report(struct kmem_cache *s, struct page *page.
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