mm/memory.c:3543 do_prot_none() error: double unlock 'spin_lock:ptl'

PATCH Ingo Molnar 2 participants 2 messages Oct 21, 2012 Kernel janitors

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Ingo Molnar

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2012-10-21 13:45 UTC #0 lore raw

Quoted 8 lines · Fengguang Wu

Hi Ingo,

FYI, there are new smatch warnings show up in

tree:   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git numa/core
head:   eb4f84b1aaad78ca07e274b81410ec9d60abe434
commit: eb4f84b1aaad78ca07e274b81410ec9d60abe434 [10/10] numa, mm: Fix 4K migration races

Quoted 15 lines

mm/memory.c:805 vm_normal_page() info: ignoring unreachable code.
mm/memory.c:805 vm_normal_page() info: ignoring unreachable code.
mm/memory.c:984 copy_pte_range() warn: inconsistent returns spin_lock:dst_ptl: locked (940) unlocked (979,984) mm/memory.c:984 copy_pte_range() warn: inconsistent returns spin_lock:__ptl: locked (979,984) unlocked (940) mm/memory.c:1532 follow_page() info: ignoring unreachable code.
mm/memory.c:1651 follow_page() warn: inconsistent returns spin_lock:ptl: locked (1628,1650,1651) unlocked (1632,1637) mm/memory.c:1651 follow_page() warn: inconsistent returns spin_lock:__ptl: locked (1632,1637) unlocked (1628,1650,1651) mm/memory.c:2688 do_wp_page() error: double unlock 'spin_lock:ptl'
mm/memory.c:2733 do_wp_page() error: double unlock 'spin_lock:ptl'
mm/memory.c:2761 do_wp_page() error: double lock 'spin_lock:__ptl'
mm/memory.c:2823 do_wp_page() error: double unlock 'spin_lock:ptl'
mm/memory.c:2853 do_wp_page() warn: inconsistent returns spin_lock:__ptl: locked (2838) unlocked (2692,2725,2849,2853)
+ mm/memory.c:3543 do_prot_none() error: double unlock 'spin_lock:ptl'
+ mm/memory.c:3557 do_prot_none() error: double lock 'spin_lock:__ptl'
mm/memory.c:3632 handle_pte_fault() warn: inconsistent returns spin_lock:ptl: locked (3613) unlocked (3591,3594,3598,3600,3605,3632)

Hm, looks like smatch got confused by the 'locked' variable?

Or can you see real problems in the code?

Thanks,

Ingo

Fengguang Wu

2012-10-21 14:24 UTC #1 lore raw

Quoted 27 lines · Ingo Molnar

Quoted 8 lines · Fengguang Wu
Hi Ingo,
FYI, there are new smatch warnings show up in
tree:   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git numa/core
head:   eb4f84b1aaad78ca07e274b81410ec9d60abe434
commit: eb4f84b1aaad78ca07e274b81410ec9d60abe434 [10/10] numa, mm: Fix 4K migration races
Quoted 15 lines
mm/memory.c:805 vm_normal_page() info: ignoring unreachable code.
mm/memory.c:805 vm_normal_page() info: ignoring unreachable code.
mm/memory.c:984 copy_pte_range() warn: inconsistent returns spin_lock:dst_ptl: locked (940) unlocked (979,984) mm/memory.c:984 copy_pte_range() warn: inconsistent returns spin_lock:__ptl: locked (979,984) unlocked (940) mm/memory.c:1532 follow_page() info: ignoring unreachable code.
mm/memory.c:1651 follow_page() warn: inconsistent returns spin_lock:ptl: locked (1628,1650,1651) unlocked (1632,1637) mm/memory.c:1651 follow_page() warn: inconsistent returns spin_lock:__ptl: locked (1632,1637) unlocked (1628,1650,1651) mm/memory.c:2688 do_wp_page() error: double unlock 'spin_lock:ptl'
mm/memory.c:2733 do_wp_page() error: double unlock 'spin_lock:ptl'
mm/memory.c:2761 do_wp_page() error: double lock 'spin_lock:__ptl'
mm/memory.c:2823 do_wp_page() error: double unlock 'spin_lock:ptl'
mm/memory.c:2853 do_wp_page() warn: inconsistent returns spin_lock:__ptl: locked (2838) unlocked (2692,2725,2849,2853)
+ mm/memory.c:3543 do_prot_none() error: double unlock 'spin_lock:ptl'
+ mm/memory.c:3557 do_prot_none() error: double lock 'spin_lock:__ptl'
mm/memory.c:3632 handle_pte_fault() warn: inconsistent returns spin_lock:ptl: locked (3613) unlocked (3591,3594,3598,3600,3605,3632)

Quoted 3 lines

Hm, looks like smatch got confused by the 'locked' variable?
Or can you see real problems in the code?

Sorry, it's actually an automated notification and I've not yet looked at the code.. I'll fix the build notification script.

Hi Dan, it looks better to only automate the 100% accurate warnings and deliver the others to internal manual check first. Would you recommend some known accurate smatch warnings? It seems to me that the "redundant null check" notes shall be always accurate. For the others, I'm not really sure.

Thanks,
Fengguang