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Differential D22124

Fix a couple of issues in the recent work on page busying.
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Authored by markj on Oct 23 2019, 2:29 PM.
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Details

Reviewers
alc
kib
jeff
Commits
rS353957: Check for bogus_page in vnode_pager_generic_getpages_done().
rS353956: Verify identity after checking for WAITFAIL in vm_page_busy_acquire().
Summary
  • vnode_pager_generic_getpages_done() must skip bogus_page.
  • vm_page_busy_acquire() must handle WAITFAIL before verifying the page's identity has not changed. If the caller does not provide this guarantee, it must use WAITFAIL or NOWAIT.
Test Plan

syzkaller found these bugs.

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Build Status
Buildable 27168
Build 25440: arc lint + arc unit

Event Timeline

markj created this revision.Oct 23 2019, 2:29 PM
Harbormaster completed remote builds in B27168: Diff 63581.Oct 23 2019, 2:29 PM
markj edited the test plan for this revision. (Show Details)Oct 23 2019, 2:30 PM
markj added reviewers: alc, kib, jeff.
kib added inline comments.Oct 23 2019, 3:00 PM
sys/vm/vnode_pager.c
1152

But how this was not the problem before ?

markj added inline comments.Oct 23 2019, 3:13 PM
sys/vm/vnode_pager.c
1152

vm_page_valid() now asserts that the page is busy, but this is not the case for bogus_page. vm_pager_assert_in() contains the same hack.

kib accepted this revision.Oct 23 2019, 3:20 PM
This revision is now accepted and ready to land.Oct 23 2019, 3:20 PM
alc accepted this revision.Oct 23 2019, 3:36 PM
Closed by commit rS353956: Verify identity after checking for WAITFAIL in vm_page_busy_acquire(). (authored by markj). · Explain WhyOct 23 2019, 5:58 PM
This revision was automatically updated to reflect the committed changes.
markj added a commit: rS353956: Verify identity after checking for WAITFAIL in vm_page_busy_acquire()..
Herald added a subscriber: imp. · View Herald TranscriptOct 23 2019, 5:58 PM
markj added a commit: rS353957: Check for bogus_page in vnode_pager_generic_getpages_done()..Oct 23 2019, 6:00 PM

Revision Contents
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PathSize
sys/
vm/
4 lines
2 lines

Diff 63581

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sys/vm/vm_page.c

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sys/vm/vnode_pager.c

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