| Message ID | 20210404163148.321346-1-vaibhav@linux.ibm.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [v2] powerpc/mm: Add cond_resched() while removing hpte mappings | expand |
| Related | show |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | Successfully applied on branch powerpc/merge (87d76f542a24ecfa797e9bd3bb56c0f19aabff57) |
| snowpatch_ozlabs/build-ppc64le | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64be | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64e | success | Build succeeded |
| snowpatch_ozlabs/build-pmac32 | success | Build succeeded |
| snowpatch_ozlabs/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 27 lines checked |
| snowpatch_ozlabs/needsstable | success | Patch has no Fixes tags |
Le 04/04/2021 à 18:31, Vaibhav Jain a écrit : > While removing large number of mappings from hash page tables for > large memory systems as soft-lockup is reported because of the time > spent inside htap_remove_mapping() like one below: > > watchdog: BUG: soft lockup - CPU#8 stuck for 23s! > <snip> > NIP plpar_hcall+0x38/0x58 > LR pSeries_lpar_hpte_invalidate+0x68/0xb0 > Call Trace: > 0x1fffffffffff000 (unreliable) > pSeries_lpar_hpte_removebolted+0x9c/0x230 > hash__remove_section_mapping+0xec/0x1c0 > remove_section_mapping+0x28/0x3c > arch_remove_memory+0xfc/0x150 > devm_memremap_pages_release+0x180/0x2f0 > devm_action_release+0x30/0x50 > release_nodes+0x28c/0x300 > device_release_driver_internal+0x16c/0x280 > unbind_store+0x124/0x170 > drv_attr_store+0x44/0x60 > sysfs_kf_write+0x64/0x90 > kernfs_fop_write+0x1b0/0x290 > __vfs_write+0x3c/0x70 > vfs_write+0xd4/0x270 > ksys_write+0xdc/0x130 > system_call+0x5c/0x70 > > Fix this by adding a cond_resched() to the loop in > htap_remove_mapping() that issues hcall to remove hpte mapping. The > call to cond_resched() is issued every HZ jiffies which should prevent > the soft-lockup from being reported. > > Suggested-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> > Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> > > --- > Changelog: > > v2: Issue cond_resched() every HZ jiffies instead of each iteration of > the loop. [ Christophe Leroy ] > --- > arch/powerpc/mm/book3s64/hash_utils.c | 13 ++++++++++++- > 1 file changed, 12 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c > index 581b20a2feaf..286e7e8cb919 100644 > --- a/arch/powerpc/mm/book3s64/hash_utils.c > +++ b/arch/powerpc/mm/book3s64/hash_utils.c > @@ -338,7 +338,7 @@ int htab_bolt_mapping(unsigned long vstart, unsigned long vend, > int htab_remove_mapping(unsigned long vstart, unsigned long vend, > int psize, int ssize) > { > - unsigned long vaddr; > + unsigned long vaddr, time_limit; > unsigned int step, shift; > int rc; > int ret = 0; > @@ -351,8 +351,19 @@ int htab_remove_mapping(unsigned long vstart, unsigned long vend, > > /* Unmap the full range specificied */ > vaddr = ALIGN_DOWN(vstart, step); > + time_limit = jiffies + HZ; > + > for (;vaddr < vend; vaddr += step) { > rc = mmu_hash_ops.hpte_removebolted(vaddr, psize, ssize); > + > + /* > + * For large number of mappings introduce a cond_resched() > + * to prevent softlockup warnings. > + */ > + if (time_after(jiffies, time_limit)) { > + cond_resched(); > + time_limit = jiffies + HZ; > + } > if (rc == -ENOENT) { > ret = -ENOENT; > continue; >
On Sun, 4 Apr 2021 22:01:48 +0530, Vaibhav Jain wrote: > While removing large number of mappings from hash page tables for > large memory systems as soft-lockup is reported because of the time > spent inside htap_remove_mapping() like one below: > > watchdog: BUG: soft lockup - CPU#8 stuck for 23s! > <snip> > NIP plpar_hcall+0x38/0x58 > LR pSeries_lpar_hpte_invalidate+0x68/0xb0 > Call Trace: > 0x1fffffffffff000 (unreliable) > pSeries_lpar_hpte_removebolted+0x9c/0x230 > hash__remove_section_mapping+0xec/0x1c0 > remove_section_mapping+0x28/0x3c > arch_remove_memory+0xfc/0x150 > devm_memremap_pages_release+0x180/0x2f0 > devm_action_release+0x30/0x50 > release_nodes+0x28c/0x300 > device_release_driver_internal+0x16c/0x280 > unbind_store+0x124/0x170 > drv_attr_store+0x44/0x60 > sysfs_kf_write+0x64/0x90 > kernfs_fop_write+0x1b0/0x290 > __vfs_write+0x3c/0x70 > vfs_write+0xd4/0x270 > ksys_write+0xdc/0x130 > system_call+0x5c/0x70 > > [...] Applied to powerpc/next. [1/1] powerpc/mm: Add cond_resched() while removing hpte mappings https://git.kernel.org/powerpc/c/a5d6a3e73acbd619dd5b7b831762b755f9e2db80 cheers
diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c index 581b20a2feaf..286e7e8cb919 100644 --- a/arch/powerpc/mm/book3s64/hash_utils.c +++ b/arch/powerpc/mm/book3s64/hash_utils.c @@ -338,7 +338,7 @@ int htab_bolt_mapping(unsigned long vstart, unsigned long vend, int htab_remove_mapping(unsigned long vstart, unsigned long vend, int psize, int ssize) { - unsigned long vaddr; + unsigned long vaddr, time_limit; unsigned int step, shift; int rc; int ret = 0; @@ -351,8 +351,19 @@ int htab_remove_mapping(unsigned long vstart, unsigned long vend, /* Unmap the full range specificied */ vaddr = ALIGN_DOWN(vstart, step); + time_limit = jiffies + HZ; + for (;vaddr < vend; vaddr += step) { rc = mmu_hash_ops.hpte_removebolted(vaddr, psize, ssize); + + /* + * For large number of mappings introduce a cond_resched() + * to prevent softlockup warnings. + */ + if (time_after(jiffies, time_limit)) { + cond_resched(); + time_limit = jiffies + HZ; + } if (rc == -ENOENT) { ret = -ENOENT; continue;
While removing large number of mappings from hash page tables for large memory systems as soft-lockup is reported because of the time spent inside htap_remove_mapping() like one below: watchdog: BUG: soft lockup - CPU#8 stuck for 23s! <snip> NIP plpar_hcall+0x38/0x58 LR pSeries_lpar_hpte_invalidate+0x68/0xb0 Call Trace: 0x1fffffffffff000 (unreliable) pSeries_lpar_hpte_removebolted+0x9c/0x230 hash__remove_section_mapping+0xec/0x1c0 remove_section_mapping+0x28/0x3c arch_remove_memory+0xfc/0x150 devm_memremap_pages_release+0x180/0x2f0 devm_action_release+0x30/0x50 release_nodes+0x28c/0x300 device_release_driver_internal+0x16c/0x280 unbind_store+0x124/0x170 drv_attr_store+0x44/0x60 sysfs_kf_write+0x64/0x90 kernfs_fop_write+0x1b0/0x290 __vfs_write+0x3c/0x70 vfs_write+0xd4/0x270 ksys_write+0xdc/0x130 system_call+0x5c/0x70 Fix this by adding a cond_resched() to the loop in htap_remove_mapping() that issues hcall to remove hpte mapping. The call to cond_resched() is issued every HZ jiffies which should prevent the soft-lockup from being reported. Suggested-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com> --- Changelog: v2: Issue cond_resched() every HZ jiffies instead of each iteration of the loop. [ Christophe Leroy ] --- arch/powerpc/mm/book3s64/hash_utils.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)