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mm/page_io.c: annotate refault stalls from swap_readpage
If a block device supports rw_page operation, it doesn't submit bios so the annotation in submit_bio() for refault stall doesn't work. It happens with zram in android, especially swap read path which could consume CPU cycle for decompress. It is also a problem for zswap which uses frontswap. Annotate swap_readpage() to account the synchronous IO overhead to prevent underreport memory pressure. [akpm@linux-foundation.org: add comment, per Johannes] Link: http://lkml.kernel.org/r/20191010152134.38545-1-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Cc: Seth Jennings <sjenning@redhat.com> Cc: Dan Streetman <ddstreet@ieee.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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parent
dd33d29a19
commit
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15
mm/page_io.c
15
mm/page_io.c
@ -22,6 +22,7 @@
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#include <linux/writeback.h>
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#include <linux/frontswap.h>
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#include <linux/blkdev.h>
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#include <linux/psi.h>
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#include <linux/uio.h>
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#include <linux/sched/task.h>
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#include <asm/pgtable.h>
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@ -354,10 +355,19 @@ int swap_readpage(struct page *page, bool synchronous)
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struct swap_info_struct *sis = page_swap_info(page);
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blk_qc_t qc;
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struct gendisk *disk;
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unsigned long pflags;
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VM_BUG_ON_PAGE(!PageSwapCache(page) && !synchronous, page);
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VM_BUG_ON_PAGE(!PageLocked(page), page);
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VM_BUG_ON_PAGE(PageUptodate(page), page);
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/*
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* Count submission time as memory stall. When the device is congested,
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* or the submitting cgroup IO-throttled, submission can be a
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* significant part of overall IO time.
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*/
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psi_memstall_enter(&pflags);
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if (frontswap_load(page) == 0) {
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SetPageUptodate(page);
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unlock_page(page);
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@ -371,7 +381,7 @@ int swap_readpage(struct page *page, bool synchronous)
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ret = mapping->a_ops->readpage(swap_file, page);
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if (!ret)
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count_vm_event(PSWPIN);
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return ret;
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goto out;
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}
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ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
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@ -382,7 +392,7 @@ int swap_readpage(struct page *page, bool synchronous)
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}
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count_vm_event(PSWPIN);
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return 0;
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goto out;
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}
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ret = 0;
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@ -418,6 +428,7 @@ int swap_readpage(struct page *page, bool synchronous)
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bio_put(bio);
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out:
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psi_memstall_leave(&pflags);
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return ret;
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}
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