swap: remove remnants of polling from read_swap_cache_async
Patch series "Per-VMA lock support for swap and userfaults", v7. When per-VMA locks were introduced in [1] several types of page faults would still fall back to mmap_lock to keep the patchset simple. Among them are swap and userfault pages. The main reason for skipping those cases was the fact that mmap_lock could be dropped while handling these faults and that required additional logic to be implemented. Implement the mechanism to allow per-VMA locks to be dropped for these cases. First, change handle_mm_fault to drop per-VMA locks when returning VM_FAULT_RETRY or VM_FAULT_COMPLETED to be consistent with the way mmap_lock is handled. Then change folio_lock_or_retry to accept vm_fault and return vm_fault_t which simplifies later patches. Finally allow swap and uffd page faults to be handled under per-VMA locks by dropping per-VMA and retrying, the same way it's done under mmap_lock. Naturally, once VMA lock is dropped that VMA should be assumed unstable and can't be used. This patch (of 6): Commit [1] introduced IO polling support duding swapin to reduce swap read latency for block devices that can be polled. However later commit [2] removed polling support. Therefore it seems safe to remove do_poll parameter in read_swap_cache_async and always call swap_readpage with synchronous=false waiting for IO completion in folio_lock_or_retry. [1] commit23955622ff
("swap: add block io poll in swapin path") [2] commit9650b453a3
("block: ignore RWF_HIPRI hint for sync dio") Link: https://lkml.kernel.org/r/20230630211957.1341547-1-surenb@google.com Link: https://lkml.kernel.org/r/20230630211957.1341547-2-surenb@google.com Signed-off-by: Suren Baghdasaryan <surenb@google.com> Suggested-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: Alistair Popple <apopple@nvidia.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christian Brauner <brauner@kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: David Howells <dhowells@redhat.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Hillf Danton <hdanton@sina.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Josef Bacik <josef@toxicpanda.com> Cc: Laurent Dufour <ldufour@linux.ibm.com> Cc: Liam R. Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes <lstoakes@gmail.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michel Lespinasse <michel@lespinasse.org> Cc: Minchan Kim <minchan@google.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Peter Xu <peterx@redhat.com> Cc: Punit Agrawal <punit.agrawal@bytedance.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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@ -217,7 +217,7 @@ static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
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ptep = NULL;
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page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
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vma, addr, false, &splug);
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vma, addr, &splug);
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if (page)
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put_page(page);
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}
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@ -262,7 +262,7 @@ static void shmem_swapin_range(struct vm_area_struct *vma,
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rcu_read_unlock();
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page = read_swap_cache_async(entry, mapping_gfp_mask(mapping),
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vma, addr, false, &splug);
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vma, addr, &splug);
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if (page)
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put_page(page);
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@ -46,7 +46,6 @@ struct folio *filemap_get_incore_folio(struct address_space *mapping,
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struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
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struct vm_area_struct *vma,
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unsigned long addr,
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bool do_poll,
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struct swap_iocb **plug);
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struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
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struct vm_area_struct *vma,
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@ -526,15 +526,14 @@ fail_put_swap:
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*/
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struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
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struct vm_area_struct *vma,
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unsigned long addr, bool do_poll,
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struct swap_iocb **plug)
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unsigned long addr, struct swap_iocb **plug)
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{
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bool page_was_allocated;
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struct page *retpage = __read_swap_cache_async(entry, gfp_mask,
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vma, addr, &page_was_allocated);
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if (page_was_allocated)
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swap_readpage(retpage, do_poll, plug);
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swap_readpage(retpage, false, plug);
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return retpage;
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}
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@ -629,7 +628,7 @@ struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask,
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struct swap_info_struct *si = swp_swap_info(entry);
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struct blk_plug plug;
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struct swap_iocb *splug = NULL;
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bool do_poll = true, page_allocated;
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bool page_allocated;
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struct vm_area_struct *vma = vmf->vma;
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unsigned long addr = vmf->address;
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@ -637,7 +636,6 @@ struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask,
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if (!mask)
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goto skip;
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do_poll = false;
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/* Read a page_cluster sized and aligned cluster around offset. */
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start_offset = offset & ~mask;
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end_offset = offset | mask;
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@ -669,7 +667,7 @@ struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t gfp_mask,
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lru_add_drain(); /* Push any new pages onto the LRU now */
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skip:
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/* The page was likely read above, so no need for plugging here */
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return read_swap_cache_async(entry, gfp_mask, vma, addr, do_poll, NULL);
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return read_swap_cache_async(entry, gfp_mask, vma, addr, NULL);
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}
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int init_swap_address_space(unsigned int type, unsigned long nr_pages)
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@ -837,7 +835,7 @@ static struct page *swap_vma_readahead(swp_entry_t fentry, gfp_t gfp_mask,
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skip:
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/* The page was likely read above, so no need for plugging here */
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return read_swap_cache_async(fentry, gfp_mask, vma, vmf->address,
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ra_info.win == 1, NULL);
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NULL);
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}
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/**
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