commit e4d27840e173491ab29c2d97017da9344e2c2526
Author: lvying <lvying6@huawei.com>
Date:   Sat Oct 31 17:57:14 2020 +0800

    ras-page-isolation: do_page_offline always considers page offline was successful
    
    do_page_offline always consider page offline was successful even if
    kernel soft/hard offline page failed.
    
    Calling rasdaemon with:
    
    	/etc/sysconfig/rasdaemon PAGE_CE_THRESHOLD="1"
    
    i.e when a page's address occurs Corrected Error, rasdaemon should
    trigger this page soft offline.
    
    However, after adding a livepatch into kernel's
    store_soft_offline_page to observe this function's return value,
    when injecting a CE into address 0x3f7ec30000, the Kernel
    lot reports:
    
    	soft_offline: 0x3f7ec30: unknown non LRU page type ffffe0000000000 ()
    	[store_soft_offline_page]return from soft_offline_page: -5
    
    While rasdaemon log reports:
    
    	rasdaemon[73711]: cpu 00:rasdaemon: Corrected Errors at 0x3f7ec30000 exceed threshold
    	rasdaemon[73711]: rasdaemon: Result of offlining page at 0x3f7ec30000: offlined
    
    using strace to record rasdaemon's system call, it reports:
    
    	strace -p 73711
    	openat(AT_FDCWD, "/sys/devices/system/memory/soft_offline_page",
    	       O_WRONLY|O_CREAT|O_TRUNC, 0666) = 28
    	fstat(28, {st_mode=S_IFREG|0200, st_size=4096, ...}) = 0
    	write(28, "0x3f7ec30000", 12)           = -1 EIO (Input/output error)
    	close(28)                               = 0
    
    So, kernel actually soft offline pfn 0x3f7ec30 failed and
    store_soft_offline_page returned -EIO. However, rasdaemon always
    considers the page offline to be successful.
    
    According to strace display, ferror was unable of detecting the
    failure of the write syscall.
    
    This patch changes fopen-fprintf-ferror-fclose process to use
    the lower I/O level, by using instead open-write-close, which
    can detect such syscall failure.
    
    Signed-off-by: lvying <lvying6@huawei.com>
    Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

diff --git a/ras-page-isolation.c b/ras-page-isolation.c
index 50e4406..dc07545 100644
--- a/ras-page-isolation.c
+++ b/ras-page-isolation.c
@@ -17,6 +17,9 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
 #include "ras-logger.h"
 #include "ras-page-isolation.h"
 
@@ -210,18 +213,22 @@ void ras_page_account_init(void)
 
 static int do_page_offline(unsigned long long addr, enum otype type)
 {
-	FILE *offline_file;
-	int err;
+	int fd, rc;
+	char buf[20];
 
-	offline_file = fopen(kernel_offline[type], "w");
-	if (!offline_file)
+	fd = open(kernel_offline[type], O_WRONLY);
+	if (fd == -1) {
+		log(TERM, LOG_ERR, "[%s]:open file: %s failed\n", __func__, kernel_offline[type]);
 		return -1;
+	}
 
-	fprintf(offline_file, "%#llx", addr);
-	err = ferror(offline_file) ? -1 : 0;
-	fclose(offline_file);
-
-	return err;
+	sprintf(buf, "%#llx", addr);
+	rc = write(fd, buf, strlen(buf));
+	if (rc < 0) {
+		log(TERM, LOG_ERR, "page offline addr(%s) by %s failed, errno:%d\n", buf, kernel_offline[type], errno);
+	}
+	close(fd);
+	return rc;
 }
 
 static void page_offline(struct page_record *pr)