| Message ID | 20240707094956.94654-2-laoar.shao@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/page_alloc: Introduce a new sysctl knob vm.pcp_batch_scale_max | expand |
Yafang Shao <laoar.shao@gmail.com> writes: > Currently, At worst, the pcp->free_count can be > (batch - 1 + (1 << MAX_ORDER)), which may exceed the expected max value of > (batch << CONFIG_PCP_BATCH_SCALE_MAX). > > This issue was identified through code review, and no real problems have > been observed. > > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > Cc: "Huang, Ying" <ying.huang@intel.com> LGTM, Thanks! Reviewed-by: "Huang, Ying" <ying.huang@intel.com> > --- > mm/page_alloc.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 2e22ce5675ca..8e2f4e1ab4f2 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2534,7 +2534,8 @@ static void free_unref_page_commit(struct zone *zone, struct per_cpu_pages *pcp, > pcp->flags &= ~PCPF_PREV_FREE_HIGH_ORDER; > } > if (pcp->free_count < (batch << CONFIG_PCP_BATCH_SCALE_MAX)) > - pcp->free_count += (1 << order); > + pcp->free_count = min(pcp->free_count + (1 << order), > + batch << CONFIG_PCP_BATCH_SCALE_MAX); > high = nr_pcp_high(pcp, zone, batch, free_high); > if (pcp->count >= high) { > free_pcppages_bulk(zone, nr_pcp_free(pcp, batch, high, free_high),
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 2e22ce5675ca..8e2f4e1ab4f2 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2534,7 +2534,8 @@ static void free_unref_page_commit(struct zone *zone, struct per_cpu_pages *pcp, pcp->flags &= ~PCPF_PREV_FREE_HIGH_ORDER; } if (pcp->free_count < (batch << CONFIG_PCP_BATCH_SCALE_MAX)) - pcp->free_count += (1 << order); + pcp->free_count = min(pcp->free_count + (1 << order), + batch << CONFIG_PCP_BATCH_SCALE_MAX); high = nr_pcp_high(pcp, zone, batch, free_high); if (pcp->count >= high) { free_pcppages_bulk(zone, nr_pcp_free(pcp, batch, high, free_high),
Currently, At worst, the pcp->free_count can be (batch - 1 + (1 << MAX_ORDER)), which may exceed the expected max value of (batch << CONFIG_PCP_BATCH_SCALE_MAX). This issue was identified through code review, and no real problems have been observed. Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Cc: "Huang, Ying" <ying.huang@intel.com> --- mm/page_alloc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)