Re: [RFC PATCH v4 1/9] mm/damon/paddr: remove page_fault access check primitive

[sashiko-bot@kernel.org]

> The page_fault access check primitive reports faults through
> damon_report_page_fault() into the global, mutex-protected
> damon_access_reports[] buffer.  A later patch in this series replaces that
> buffer with per-context rings fed only by perf-event probes, which leaves
> the page-fault producer with nowhere to report.  Remove the producer here
> so no report is silently dropped.
> 
> Remove damon_pa_prepare_access_checks_faults() and its supporting
> damon_pa_change_protection()/damon_pa_change_protection_one() helpers,
> and the page_fault dispatch in damon_pa_prepare_access_checks().  Remove
> damon_report_page_fault() and its sole caller, do_damon_page(), along
> with the two page-fault-handler dispatch sites in mm/memory.c that
> selected it over the ordinary NUMA-hinting fault path.
> 
> Writing Y to the sysfs page_fault file now returns -EOPNOTSUPP, and core
> validation rejects a context with page_fault set, so a configuration
> cannot select a primitive that no longer reports and have every region
> read as cold.  With page_fault gone, page_table is the only access check
> primitive left, so a context must enable it.  This leaves MM_CP_DAMON
> with no user that sets it; its check in mm/mprotect.c is left for a
> separate cleanup.
> 
> Signed-off-by: Ravi Jonnalagadda <ravis.opensrc@gmail.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20261005-damon-perf-rfc-v3-send-2026-10-03-v4-0-b03452e137f3@gmail.com?part=1