[PATCH 0/20] mmu: arch/mm: Port OOM changes to arch page fault handlers.

[Kautuk Consul <consul.kautuk@xxxxxxxxx>]

Commit d065bd810b6deb67d4897a14bfe21f8eb526ba99
(mm: retry page fault when blocking on disk transfer) and
commit 37b23e0525d393d48a7d59f870b3bc061a30ccdb
(x86,mm: make pagefault killable)

The above commits introduced changes into the x86 pagefault handler
for making the page fault handler retryable as well as killable.

These changes reduce the mmap_sem hold time, which is crucial
during OOM killer invocation.

I was facing hang and livelock problems on my ARM and MIPS boards when
I invoked OOM by running the stress_32k.c test-case attached to this email.

Since both the ARM and MIPS porting chainges were accepted, me and my
co-worker decided to take the initiative to port these changes to all other
MMU based architectures.

Please review and do write back if there is any way I need to
improve/rewrite any
of these patches.

Signed-off-by: Mohd. Faris <mohdfarisq2010@xxxxxxxxx>
Signed-off-by: Kautuk Consul <consul.kautuk@xxxxxxxxx>
---

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <unistd.h>

#define ALLOC_BYTE 512*1024
#define COUNT 50

void *alloc_function_one( void *ptr );
void *alloc_function_two( void *ptr );
void *alloc_function_three( void *ptr );
void *alloc_function_four( void *ptr );
void *alloc_function_five( void *ptr );
void *enable_function( void *ptr );


int main(int argc, char *argv[])
{
	pthread_t thread1, thread2, thread3, thread4, thread5;
	char *message1 = "Thread 1";
	char *message2 = "Thread 2";
	char *message3 = "Thread 3";
	char *message4 = "Thread 4";
	char *message5 = "Thread 5";
	int iret1 = -1;
	int iret2 = -1;
	int iret3 = -1;
	int iret4 = -1;
	int iret5 = -1;
	fork();
	iret1 = pthread_create( &thread1, NULL, alloc_function_one, (void*) message1);
	iret2 = pthread_create( &thread2, NULL, alloc_function_two, (void*) message2);
	iret2 = pthread_create( &thread3, NULL, alloc_function_three, (void*) message2);
	iret2 = pthread_create( &thread4, NULL, alloc_function_four, (void*) message2);
	iret2 = pthread_create( &thread5, NULL, alloc_function_five, (void*) message2);

	pthread_join( thread1, NULL);
	pthread_join( thread2, NULL);
	pthread_join( thread3, NULL);
	pthread_join( thread4, NULL);
	pthread_join( thread5, NULL);

	printf("Thread 1 returns: %d\n",iret1);
	printf("Thread 2 returns: %d\n",iret2);
	printf("Thread 3 returns: %d\n",iret3);
	printf("Thread 4 returns: %d\n",iret4);
	printf("Thread 5 returns: %d\n",iret5);
	exit(0);
}

void *alloc_function_two( void *ptr )
{
	char *message;
	message = (char *) ptr;
	void *myblock[COUNT];
	int i= 0,j=0;
	int freed=0;
	printf("message_alloc  \n");
	while(1)
	{
		memset(myblock,0,sizeof(myblock));
		printf("message_alloc %s \n",message);
		for(i=0;i< COUNT ;i++)
		{
			myblock[i] = (void *) malloc(ALLOC_BYTE);
			memset(myblock[i],1, ALLOC_BYTE);
		}
	}
}


void *alloc_function_one( void *ptr )
{
	char *message;
	message = (char *) ptr;
	void *myblock[COUNT];
	int i= 0,j=0;
	int freed=0;
	printf("message_alloc  \n");
	while(1)
	{
		memset(myblock,0,sizeof(myblock));
		printf("message_alloc %s \n",message);
		for(i=0;i< COUNT ;i++)
		{
			myblock[i] = (void *) malloc(ALLOC_BYTE);
			memset(myblock[i],1, ALLOC_BYTE);
		}
	}
}

void *alloc_function_three( void *ptr )
{
       char *message;
        message = (char *) ptr;
        void *myblock[COUNT];
        int i= 0,j=0;
        int freed=0;
        printf("message_alloc  \n");
        while(1)
        {
                memset(myblock,0,sizeof(myblock));
                printf("message_alloc %s \n",message);
                for(i=0;i< COUNT ;i++)
                {
                        myblock[i] = (void *) malloc(ALLOC_BYTE);
                        memset(myblock[i],1, ALLOC_BYTE);
                }
        }
}
void *alloc_function_four( void *ptr )
{
       char *message;
        message = (char *) ptr;
        void *myblock[COUNT];
        int i= 0,j=0;
        int freed=0;
        printf("message_alloc  \n");
        while(1)
        {
                memset(myblock,0,sizeof(myblock));
                printf("message_alloc %s \n",message);
                for(i=0;i< COUNT ;i++)
                {
                        myblock[i] = (void *) malloc(ALLOC_BYTE);
                        memset(myblock[i],1, ALLOC_BYTE);
                }
        }
}
void *alloc_function_five( void *ptr )
{
       char *message;
        message = (char *) ptr;
        void *myblock[COUNT];
        int i= 0,j=0;
        int freed=0;
        printf("message_alloc  \n");
        while(1)
        {
                memset(myblock,0,sizeof(myblock));
                printf("message_alloc %s \n",message);
                for(i=0;i< COUNT ;i++)
                {
                        myblock[i] = (void *) malloc(ALLOC_BYTE);
                        memset(myblock[i],1, ALLOC_BYTE);
                }
        }
}