[Xen-devel] [PATCH] Make XEN_DOMCTL_destroydomain hypercall return error

[Isaku Yamahata <yamahata@xxxxxxxxxxxxx>]

Hi.

Soft lockup warning pops up when destroying a domain with large memory
on IA64. It is because the domain destroy hypercall which frees all
pages of the domain takes too long.
This patch is the common part of the patch set which eliminates it.
The remaining arch (IA64) specific part is thet make the hypercall
return -EAGAIN if necessary and make kernel repeat issuing it until
success. I will send the remaining patches to xen-ia64-devel if this
patch is acceptable.

Another approach would be that the hypercall returns immidiately 
sucessfully and the actual work is done backgroundly in xen.
Since the thread in xen isn't supported currently, it would be
somewhat complicated one using timer or soft interrupt handler.
So I chose repeating the hypercall.


# HG changeset patch
# User yamahata@xxxxxxxxxxxxx
# Date 1186646122 -32400
# Node ID 68e56e0339b6bf42a694c2c435106b2a7bf286c3
# Parent  484848f240e80cd403b0425fa35d7257bbc18cc2
Make XEN_DOMCTL_destroydomain hypercall return error.
This is preparetion to prevent soft lockup warning when domain destroy and
doesn't change existing behaviour.

When domain memory size is very large, the domain destroy hypercall takes
too long to trigger soft lockup warning because the hypercall frees all
pages of the domain.
To prevent soft lockup message, the hypercall returns -EAGAIN if necessary
and kernel repeats issuing it until success.
The remaining part is arch specific.
PATCHNAME: preparetion_destroy_domain_soft_lockup

Signed-off-by: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>

diff -r 484848f240e8 -r 68e56e0339b6 xen/arch/ia64/xen/domain.c
--- a/xen/arch/ia64/xen/domain.c        Wed Aug 08 17:50:24 2007 +0100
+++ b/xen/arch/ia64/xen/domain.c        Thu Aug 09 16:55:22 2007 +0900
@@ -932,7 +932,7 @@ static void relinquish_memory(struct dom
     spin_unlock_recursive(&d->page_alloc_lock);
 }
 
-void domain_relinquish_resources(struct domain *d)
+int domain_relinquish_resources(struct domain *d)
 {
     /* Relinquish guest resources for VT-i domain. */
     if (d->vcpu[0] && VMX_DOMAIN(d->vcpu[0]))
@@ -950,6 +950,8 @@ void domain_relinquish_resources(struct 
 
     /* Free page used by xen oprofile buffer */
     free_xenoprof_pages(d);
+
+    return 0;
 }
 
 unsigned long
diff -r 484848f240e8 -r 68e56e0339b6 xen/arch/powerpc/domain.c
--- a/xen/arch/powerpc/domain.c Wed Aug 08 17:50:24 2007 +0100
+++ b/xen/arch/powerpc/domain.c Thu Aug 09 16:55:22 2007 +0900
@@ -313,13 +313,13 @@ static void relinquish_memory(struct dom
     spin_unlock_recursive(&d->page_alloc_lock);
 }
 
-void domain_relinquish_resources(struct domain *d)
+int domain_relinquish_resources(struct domain *d)
 {
     relinquish_memory(d, &d->xenpage_list);
     relinquish_memory(d, &d->page_list);
     xfree(d->arch.foreign_mfns);
     xfree(d->arch.p2m);
-    return;
+    return 0;
 }
 
 void arch_dump_domain_info(struct domain *d)
diff -r 484848f240e8 -r 68e56e0339b6 xen/arch/x86/domain.c
--- a/xen/arch/x86/domain.c     Wed Aug 08 17:50:24 2007 +0100
+++ b/xen/arch/x86/domain.c     Thu Aug 09 16:55:22 2007 +0900
@@ -1717,7 +1717,7 @@ static void vcpu_destroy_pagetables(stru
     v->arch.cr3 = 0;
 }
 
-void domain_relinquish_resources(struct domain *d)
+int domain_relinquish_resources(struct domain *d)
 {
     struct vcpu *v;
 
@@ -1754,6 +1754,8 @@ void domain_relinquish_resources(struct 
 
     if ( is_hvm_domain(d) )
         hvm_domain_relinquish_resources(d);
+
+    return 0;
 }
 
 void arch_dump_domain_info(struct domain *d)
diff -r 484848f240e8 -r 68e56e0339b6 xen/common/domain.c
--- a/xen/common/domain.c       Wed Aug 08 17:50:24 2007 +0100
+++ b/xen/common/domain.c       Thu Aug 09 16:55:22 2007 +0900
@@ -298,26 +298,35 @@ struct domain *rcu_lock_domain_by_id(dom
 }
 
 
-void domain_kill(struct domain *d)
-{
+int domain_kill(struct domain *d)
+{
+    int rc = 0;
     domain_pause(d);
 
     /* Already dying? Then bail. */
-    if ( test_and_set_bool(d->is_dying) )
+    if ( test_and_set_bool(d->is_dying) &&
+         test_and_set_bool(d->is_relinquishing_resources))
     {
         domain_unpause(d);
-        return;
-    }
-
+        return 0;
+    }
+
+    gnttab_release_mappings(d);
+    rc = domain_relinquish_resources(d);
+    if (rc != 0) {
+        BUG_ON(rc != -EAGAIN);
+        /* clear_bool() isn't defined */
+        (void)test_and_clear_bool(d->is_relinquishing_resources);
+        return rc;
+    }
     evtchn_destroy(d);
-    gnttab_release_mappings(d);
-    domain_relinquish_resources(d);
     put_domain(d);
 
     /* Kick page scrubbing after domain_relinquish_resources(). */
     page_scrub_kick();
 
     send_guest_global_virq(dom0, VIRQ_DOM_EXC);
+    return 0;
 }
 
 
diff -r 484848f240e8 -r 68e56e0339b6 xen/common/domctl.c
--- a/xen/common/domctl.c       Wed Aug 08 17:50:24 2007 +0100
+++ b/xen/common/domctl.c       Thu Aug 09 16:55:22 2007 +0900
@@ -397,10 +397,7 @@ long do_domctl(XEN_GUEST_HANDLE(xen_domc
         {
             ret = -EINVAL;
             if ( d != current->domain )
-            {
-                domain_kill(d);
-                ret = 0;
-            }
+                ret = domain_kill(d);
             rcu_unlock_domain(d);
         }
     }
diff -r 484848f240e8 -r 68e56e0339b6 xen/include/asm-ia64/domain.h
--- a/xen/include/asm-ia64/domain.h     Wed Aug 08 17:50:24 2007 +0100
+++ b/xen/include/asm-ia64/domain.h     Thu Aug 09 16:55:22 2007 +0900
@@ -18,7 +18,6 @@ struct tlb_track;
 struct tlb_track;
 #endif
 
-extern void domain_relinquish_resources(struct domain *);
 struct vcpu;
 extern void relinquish_vcpu_resources(struct vcpu *v);
 extern void vcpu_share_privregs_with_guest(struct vcpu *v);
diff -r 484848f240e8 -r 68e56e0339b6 xen/include/xen/domain.h
--- a/xen/include/xen/domain.h  Wed Aug 08 17:50:24 2007 +0100
+++ b/xen/include/xen/domain.h  Thu Aug 09 16:55:22 2007 +0900
@@ -45,7 +45,7 @@ int arch_set_info_guest(struct vcpu *, v
 int arch_set_info_guest(struct vcpu *, vcpu_guest_context_u);
 void arch_get_info_guest(struct vcpu *, vcpu_guest_context_u);
 
-void domain_relinquish_resources(struct domain *d);
+int domain_relinquish_resources(struct domain *d);
 
 void dump_pageframe_info(struct domain *d);
 
diff -r 484848f240e8 -r 68e56e0339b6 xen/include/xen/sched.h
--- a/xen/include/xen/sched.h   Wed Aug 08 17:50:24 2007 +0100
+++ b/xen/include/xen/sched.h   Thu Aug 09 16:55:22 2007 +0900
@@ -192,7 +192,9 @@ struct domain
     bool_t           is_polling;
     /* Is this guest dying (i.e., a zombie)? */
     bool_t           is_dying;
-    /* Domain is paused by controller software? */
+    /* Is thin guest relinquishing resources? */
+    bool_t           is_relinquishing_resources;
+    /* Domain is paused by controller softwares? */
     bool_t           is_paused_by_controller;
 
     /* Guest has shut down (inc. reason code)? */
@@ -335,7 +337,7 @@ static inline struct domain *rcu_lock_cu
 
 struct domain *get_domain_by_id(domid_t dom);
 void domain_destroy(struct domain *d);
-void domain_kill(struct domain *d);
+int domain_kill(struct domain *d);
 void domain_shutdown(struct domain *d, u8 reason);
 void domain_resume(struct domain *d);
 void domain_pause_for_debugger(void);


-- 
yamahata

Attachment: 15710_68e56e0339b6_preparetion_destroy_domain_soft_lockup.patch
Description: Text Data

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