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Subject[PATCH 0/4] Verification and debugging of memory initialisation V4
Date
Boot initialisation is very complex, with significant numbers of
architecture-specific routines, hooks and code ordering. While significant
amounts of the initialisation is architecture-independent, it trusts
the data received from the architecture layer. This is a mistake, and has
resulted in a number of difficult-to-diagnose bugs. This patchset adds some
validation and tracing to memory initialisation. It also introduces a few
basic defensive measures. The validation code can be explicitly disabled
for embedded systems.

I believe it's ready for a round of testing in -mm. The patches are based
against 2.6.25-mm1.

Changelog since V3
o (Andrew) Only allow disabling of verification checks on CONFIG_EMBEDDED
o (Andy Whitcroft) Documentation and leader fixups
o (Andy) Rename mminit_debug_printk to mminit_dprintk for consistency
o (Andy) Rename mminit_verify_pageflags to mminit_verify_pageflags_layout
o (Andy) Rename mminit_validate_physlimits to mminit_validate_memmodel_limits
o (Andy) Fix page->flags bitmap overlap checks
o (Andy) Fix argument type for level in mminit_dprintk()
o (Mel) Add WARNING error level that is the default logging level for
mminit_loglevel=. Messages printed at this or lower levels will use
KERN_WARNING for the printk loglevel. Otherwise KERN_DEBUG is used.

Changelog since V2
o (Mel) Rebase to 2.6.25-mm1 and rewrite zonelist dump
o (Mel) Depend on DEBUG_VM instead of DEBUG_KERNEL
o (Mel) Use __meminitdata instead of __initdata for logging level
o (Christoph) Get rid of FLAGS_RESERVED references
o (Christoph) Print out flag usage information
o (Ingo) Default do the verifications on DEBUG_VM and instead control the
level of verbose logging with mminit_loglevel= instead of
mminit_debug_level=
o (Anon) Log at KERN_DEBUG level
o (Anon) Optimisation to the mminit_debug_printk macro

Changelog since V1
o (Ingo) Make memory initialisation verification a DEBUG option depending on
DEBUG_KERNEL option. By default it will then to verify structures but
tracing can be enabled via the command-line. Without the CONFIG option,
checks will still be made on PFN ranges passed by the architecture-specific
code and a warning printed once if a problem is encountered
o (Ingo) WARN_ON_ONCE when PFNs from the architecture violate SPARSEMEM
limitations. The warning should be "harmless" as the system will boot
regardless but it acts as a reminder that bad input is being used.
o (Anon) Convert mminit_debug_printk() to a macro
o (Anon) Spelling mistake corrections
o (Anon) Use of KERN_CONT properly for multiple printks
o (Mel) Reshuffle the patches so that the zonelist printing is at the
end of the patchset. This is because -mm requires a different patch to
print zonelists and this allows the end patch to be temporarily dropped
when testing against -mm
o (Mel) Rebase on top of Ingo's sparsemem fix for easier testing
o (Mel) Document mminit_debug_level=
o (Mel) Fix check on pageflags where the masks were not being shifted
o (Mel) The zone ID should should have used page_zonenum not page_zone_id
o (Mel) Iterate all zonelists correctly
o (Mel) Correct typo of SECTIONS_SHIFT

--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab


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