linux.git/mm/damon, branch v6.14

mm/damon/core: initialize damos->walk_completed in damon_new_scheme()

2025-03-17T00:40:23+00:00

The function for allocating and initialize a 'struct damos' object,
damon_new_scheme(), is not initializing damos->walk_completed field.  Only
damos_walk_complete() is setting the field.  Hence the field will be
eventually set and used correctly from second damos_walk() call for the
scheme.  But the first damos_walk() could mistakenly not walk on the
regions.  Actually, a common usage of DAMOS for taking an access pattern
snapshot is installing a monitoring-purpose DAMOS scheme, doing
damos_walk() to retrieve the snapshot, and then removing the scheme. 
DAMON user-space tool (damo) also gets runtime snapshot in the way.  Hence
the problem can continuously happen in such use cases.  Initialize it
properly in the allocation function.

Link: https://lkml.kernel.org/r/20250228174450.41472-1-sj@kernel.org
Fixes: bf0eaba0ff9c ("mm/damon/core: implement damos_walk()")
Signed-off-by: SeongJae Park 
Signed-off-by: Andrew Morton

mm/damon: respect core layer filters' allowance decision on ops layer

2025-03-17T00:40:23+00:00

Filtering decisions are made in filters evaluation order.  Once a decision
is made by a filter, filters that scheduled to be evaluated after the
decision-made filter should just respect it.  This is the intended and
documented behavior.  Since core layer-handled filters are evaluated
before operations layer-handled filters, decisions made on core layer
should respected by ops layer.

In case of reject filters, the decision is respected, since core
layer-rejected regions are not passed to ops layer.  But in case of allow
filters, ops layer filters don't know if the region has passed to them
because it was allowed by core filters or just because it didn't match to
any core layer.  The current wrong implementation assumes it was due to
not matched by any core filters.  As a reuslt, the decision is not
respected.  Pass the missing information to ops layer using a new filed in
'struct damos', and make the ops layer filters respect it.

Link: https://lkml.kernel.org/r/20250228175336.42781-1-sj@kernel.org
Fixes: 491fee286e56 ("mm/damon/core: support damos_filter->allow")
Signed-off-by: SeongJae Park 
Signed-off-by: Andrew Morton

mm/damon/core: use str_high_low() helper in damos_wmark_wait_us()

2025-01-26T04:22:46+00:00

Remove hard-coded strings by using the str_high_low() helper function.

Link: https://lkml.kernel.org/r/20250116204216.106999-2-thorsten.blum@linux.dev
Signed-off-by: Thorsten Blum 
Reviewed-by: SeongJae Park 
Signed-off-by: Andrew Morton

mm/damon/paddr: improve readability of damon_pa_stat

2025-01-26T04:22:41+00:00

damon_pa_stat contains an unnecessary goto statement, and the if/else can
be re-written to be more readable.

This patch is written on top of SJ's patch series [1], which in turn is
written on top of another one of his series [2].

[1] https://lore.kernel.org/all/20241219040327.61902-1-sj@kernel.org/
[2] https://lore.kernel.org/all/20241213215306.54778-1-sj@kernel.org/

Link: https://lkml.kernel.org/r/20250113210201.446051-1-joshua.hahnjy@gmail.com
Signed-off-by: Joshua Hahn 
Reviewed-by: SeongJae Park 
Signed-off-by: Andrew Morton

mm/damon/paddr: increment pa_stat damon address range by folio size

2025-01-26T04:22:41+00:00

This is to avoid going through all the pages in a folio.  For folio_size >
PAGE_SIZE, damon_get_folio will return NULL for tail pages, so the for
loop in those instances will be a nop.  Have a more efficient loop by just
incrementing the address by folio_size.

Link: https://lkml.kernel.org/r/20250113190738.1156381-1-usamaarif642@gmail.com
Signed-off-by: Usama Arif 
Reviewed-by: SeongJae Park 
Signed-off-by: Andrew Morton

mm/damon/sysfs-schemes: add a file for setting damos_filter->allow

2025-01-26T04:22:32+00:00

Only kernel-space DAMON API users can use inclusive DAMOS filters.  Add a
sysfs file named 'allow' under DAMOS filter directory of DAMON sysfs
interface, to let the user-space users use inclusive DAMOS filters.

Link: https://lkml.kernel.org/r/20250109175126.57878-7-sj@kernel.org
Signed-off-by: SeongJae Park 
Cc: Jonathan Corbet 
Signed-off-by: Andrew Morton

mm/damon: add 'allow' argument to damos_new_filter()

2025-01-26T04:22:32+00:00

DAMON API users should set damos_filter->allow manually to use a DAMOS
allow-filter, since damos_new_filter() unsets the field always.  It is
cumbersome and easy to mistake.  Add an arugment for setting the field to
damos_new_filter().

Link: https://lkml.kernel.org/r/20250109175126.57878-6-sj@kernel.org
Signed-off-by: SeongJae Park 
Cc: Jonathan Corbet 
Signed-off-by: Andrew Morton

mm/damon/paddr: support damos_filter->allow

2025-01-26T04:22:32+00:00

Respect damos_filter->allow from 'paddr', which is a DAMON operations set
implementation for the physical address space and supports a few types of
region-internal DAMOS filters (anon, memcg and young).  The change is
similar to that of the previous commit for core layer update.

Link: https://lkml.kernel.org/r/20250109175126.57878-5-sj@kernel.org
Signed-off-by: SeongJae Park 
Cc: Jonathan Corbet 
Signed-off-by: Andrew Morton

mm/damon/core: support damos_filter->allow

2025-01-26T04:22:32+00:00

DAMOS filters supports allowing behavior, but the core layer's DAMOS
filters handling logic still assumes only rejecting (filtering-out)
behavior.  Update the logic to aware of and respect the behavioral
decision by reading damos_filter->allow when making the decision to
exclude a region or not.

Link: https://lkml.kernel.org/r/20250109175126.57878-4-sj@kernel.org
Signed-off-by: SeongJae Park 
Cc: Jonathan Corbet 
Signed-off-by: Andrew Morton

mm/damon/core: add damos_filter->allow field

2025-01-26T04:22:31+00:00

DAMOS filters work as only exclusive (reject) filters.  This makes it easy
to be confused, and restrictive at combining multiple filters for covering
various types of memory.

Add a field named 'allow' to damos_filter.  The field will be used to
indicate whether the filter should work for inclusion or exclusion.  To
keep the old behavior, set it as 'false' (work as exclusive filter) by
default, from damos_new_filter().

Following two commits will make the core and operations set layers, which
handles damos_filter objects, respect the field, respectively.

Link: https://lkml.kernel.org/r/20250109175126.57878-3-sj@kernel.org
Signed-off-by: SeongJae Park 
Cc: Jonathan Corbet 
Signed-off-by: Andrew Morton