| Message ID | 20190726050440.24798-3-bharata@linux.ibm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Memory unplug fixes for radix guests | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | Successfully applied on branch next (f3365d1a959d5c6527efe3d38276acc9b58e3f3f) |
| snowpatch_ozlabs/build-ppc64le | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64be | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64e | warning | Build succeeded but added 1 new sparse warnings |
| snowpatch_ozlabs/build-pmac32 | warning | Build succeeded but added 1 new sparse warnings |
| snowpatch_ozlabs/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 28 lines checked |
On Fri, Jul 26, 2019 at 10:34:40AM +0530, Bharata B Rao wrote: >remove_pagetable() isn't freeing PUD table. This causes memory >leak during memory unplug. Fix this. On x86, this is intentional. See af2cf278ef4f ("x86/mm/hotplug: Don't remove PGD entries in remove_pagetable()") 98fe3633c5a4 ("x86/mm/hotplug: Fix BUG_ON() after hot-remove by not freeing PUD") Does their reasoning apply to powerpc as well?
On Tue, Jul 30, 2019 at 02:37:16PM -0500, Reza Arbab wrote: > On Fri, Jul 26, 2019 at 10:34:40AM +0530, Bharata B Rao wrote: > > remove_pagetable() isn't freeing PUD table. This causes memory > > leak during memory unplug. Fix this. > > On x86, this is intentional. See > > af2cf278ef4f ("x86/mm/hotplug: Don't remove PGD entries in remove_pagetable()") > 98fe3633c5a4 ("x86/mm/hotplug: Fix BUG_ON() after hot-remove by not freeing PUD") > > Does their reasoning apply to powerpc as well? x86 seems to maintain some global pgd list that needs to sync'ed up when PGD entry is freed. Since powerpc doesn't have that equivalent I don't see that reasoning applying here. However if there is more to it than just this, then I am not sure. Regards, Bharata.
diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c index c440446ee00f..860eb37736c0 100644 --- a/arch/powerpc/mm/book3s64/radix_pgtable.c +++ b/arch/powerpc/mm/book3s64/radix_pgtable.c @@ -783,6 +783,21 @@ static void free_pmd_table(pmd_t *pmd_start, pud_t *pud) pud_clear(pud); } +static void free_pud_table(pud_t *pud_start, pgd_t *pgd) +{ + pud_t *pud; + int i; + + for (i = 0; i < PTRS_PER_PUD; i++) { + pud = pud_start + i; + if (!pud_none(*pud)) + return; + } + + pud_free(&init_mm, pud_start); + pgd_clear(pgd); +} + struct change_mapping_params { pte_t *pte; unsigned long start; @@ -953,6 +968,7 @@ static void __meminit remove_pagetable(unsigned long start, unsigned long end) pud_base = (pud_t *)pgd_page_vaddr(*pgd); remove_pud_table(pud_base, addr, next); + free_pud_table(pud_base, pgd); } spin_unlock(&init_mm.page_table_lock);
remove_pagetable() isn't freeing PUD table. This causes memory leak during memory unplug. Fix this. Signed-off-by: Bharata B Rao <bharata@linux.ibm.com> --- arch/powerpc/mm/book3s64/radix_pgtable.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)