On Thu, Oct 22, 2015 at 10:21:36AM +0900, Minchan Kim wrote: > Hello Hugh, > > On Wed, Oct 21, 2015 at 05:59:59PM -0700, Hugh Dickins wrote: > > On Thu, 22 Oct 2015, Minchan Kim wrote: > > > > > > I added the code to check it and queued it again but I had another oops > > > in this time but symptom is related to anon_vma, too. > > > (kernel is based on recent mmotm + unconditional mkdirty for bug fix) > > > It seems page_get_anon_vma returns NULL since the page was not page_mapped > > > at that time but second check of page_mapped right before try_to_unmap seems > > > to be true. > > > > > > Adding 4191228k swap on /dev/vda5. Priority:-1 extents:1 across:4191228k FS > > > Adding 4191228k swap on /dev/vda5. Priority:-1 extents:1 across:4191228k FS > > > page:ffffea0001cfbfc0 count:3 mapcount:1 mapping:ffff88007f1b5f51 index:0x600000aff > > > flags: 0x4000000000048019(locked|uptodate|dirty|swapcache|swapbacked) > > > page dumped because: VM_BUG_ON_PAGE(PageAnon(page) && !PageKsm(page) && !anon_vma) > > > > That's interesting, that's one I added in my page migration series. > > Let me think on it, but it could well relate to the one you got before. > > I will roll back to mm/madv_free-v4.3-rc5-mmotm-2015-10-15-15-20 > instead of next-20151021 to remove noise from your migration cleanup > series and will test it again. > If it is fixed, I will test again with your migration patchset, then. I tested mmotm-2015-10-15-15-20 with test program I attach for a long time. Therefore, there is no patchset from Hugh's migration patch in there. And I added below debug code with request from Kirill to all test kernels. diff --git a/mm/rmap.c b/mm/rmap.c index ddfb9be72366..1c23b70b1f57 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -513,6 +513,13 @@ struct anon_vma *page_lock_anon_vma_read(struct page *page) anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); root_anon_vma = READ_ONCE(anon_vma->root); + + if (root_anon_vma == NULL) { + printk("anon_vma %p refcount %d\n", anon_vma, + atomic_read(&anon_vma->refcount)); + VM_BUG_ON_PAGE(1, page); + } + if (down_read_trylock(&root_anon_vma->rwsem)) { /* * If the page is still mapped, then this anon_vma is still 1. mmotm-2015-10-15-15-20 + kirill's pte_mkdirty 1st trial: Adding 4191228k swap on /dev/vda5. Priority:-1 extents:1 across:4191228k FS Adding 4191228k swap on /dev/vda5. Priority:-1 extents:1 across:4191228k FS BUG: Bad rss-counter state mm:ffff88007f1ed780 idx:1 val:488 BUG: Bad rss-counter state mm:ffff88007f1ed780 idx:2 val:24 2nd trial: Adding 4191228k swap on /dev/vda5. Priority:-1 extents:1 across:4191228k FS BUG: Bad rss-counter state mm:ffff8800a5cca680 idx:1 val:512 Adding 4191228k swap on /dev/vda5. Priority:-1 extents:1 across:4191228k FS 2. mmotm-2015-10-15-15-20-no-madvise_free, IOW it means git head for 54bad5da4834 arm64: add pmd_[dirty|mkclean] for THP. 1st trial: Adding 4191228k swap on /dev/vda5. Priority:-1 extents:1 across:4191228k FS BUG: Bad rss-counter state mm:ffff88007f4c2d80 idx:1 val:511 BUG: Bad rss-counter state mm:ffff88007f4c2d80 idx:2 val:1 2nd trial: Adding 4191228k swap on /dev/vda5. Priority:-1 extents:1 across:4191228k FS Adding 4191228k swap on /dev/vda5. Priority:-1 extents:1 across:4191228k FS anon_vma ffff880000089aa0 refcount 0 page:ffffea0001a2ea40 count:3 mapcount:1 mapping:ffff880000089aa1 index:0x6000047a9 I tested it with KVM which guest system has 12 core and 3G memory. In mmotm-2015-10-15-15-20-no-madvise_free, I tweaked test program does madvise_dontneed intead of madvise_free via below patch For the testing, gcc -o oops oops.c ./memcg_test.sh I will be off from now on so please understand late response but I hope my test program will reproduce it in your machine. diff --git a/oops.c b/oops.c index e50330a..c8298f8 100644 --- a/oops.c +++ b/oops.c @@ -8,7 +8,7 @@ #include <errno.h> #include <signal.h> -#define MADV_FREE 5 +#define MADV_FREE 4 int pid;
Attachment:
memcg_move_task.sh
Description: Bourne shell script
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memcg_test.sh
Description: Bourne shell script
#include <sys/types.h> #include <stdlib.h> #include <sys/mman.h> #include <stdlib.h> #include <string.h> #include <stdio.h> #include <unistd.h> #include <errno.h> #include <signal.h> #define MADV_FREE 4 int pid; void sig_handler(int signo) { printf("pid %d sig received %d\n", pid, signo); exit(1); } void free_bufs(void **bufs, unsigned long buf_count, unsigned long buf_size) { int i; for (i = 0; i < buf_count; i++) { if (bufs[i] != NULL) { munmap(bufs[i], buf_size); bufs[i] = NULL; } } } void alloc_bufs(void **bufs, unsigned long buf_count, unsigned long buf_size) { int i; time_t rawtime; struct tm * timeinfo; void *addr = (void*)0x600000000000; for (i = 0; i < buf_count; i++) { void *ptr = NULL; ptr = mmap(addr, buf_size, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE|MAP_FIXED, 0, 0); if (ptr == MAP_FAILED) { char bufs[64]; sprintf(bufs, "cat /proc/%d/maps", pid); printf("error to allocate %p\n", addr); system(bufs); exit(1); } addr += buf_size; bufs[i] = ptr; } } void fill_bufs(void **bufs, unsigned long buf_count, unsigned long buf_size) { int i; char msg[64] = {0, }; for (i = 0; i < buf_count; i++) memset(bufs[i], 'a' + i, buf_size); sprintf(msg, "pid %d buf_count %ld complete", pid, buf_count); } void madvise_bufs(void **bufs, unsigned long buf_count, unsigned long buf_size, int advise) { int i, ret; for (i = 0; i < buf_count; i++) { retry: if (ret = madvise(bufs[i], buf_size, advise)) { perror("fail to madvise\n"); if (ret == EAGAIN) { sleep(1); goto retry; } exit(1); } } } void madvise_free_bufs(void **bufs, unsigned long buf_count, unsigned long buf_size) { int i; for (i = 0; i < buf_count; i++) { if (madvise(bufs[i], buf_size, MADV_FREE)) { printf("[%d] bufs[%d] %p madvise_free fail\n", pid, i, bufs[i]); } } } void check_madvise_bufs(void **bufs, unsigned long buf_count, unsigned long buf_size, int freeable) { int i, j; for (i = 0; i < buf_count; i++) { char tmp; void *buf = bufs[i]; for (j = 0; j < buf_size; j++) { int ret; unsigned long addr; tmp = *(char*)(buf + j); /* The page was not purged */ if (tmp == 'a' + i) continue; /* The page was purged */ if (freeable && (int)tmp == 0) continue; /* Something wrong happens */ addr = (unsigned long)(buf + j); printf("pid %d bufaddr %p ofs %d freeable %d expected %c but %c\n", pid, buf, j, freeable, 'a' + i, tmp); exit(1); } } } int main(int argc, char *argv[]) { int i, ret, advise; unsigned long buf_size, buf_count, loop; void **bufs; pid = getpid(); if (argc != 4) { printf("check your argument\n"); return 1; } buf_size = atol(argv[1]); buf_count = atol(argv[2]); advise = atol(argv[3]); if (buf_size & ((2<<20) - 1)) { printf("buf_size should be 2M aligned\n"); return 1; } printf("[%d] buf size %ld buf_count %ld advise %d\n", pid, buf_size, buf_count, advise); if (signal(SIGINT, sig_handler) == SIG_ERR) { printf("Fail to register signal handler\n"); return 1; } if (signal(SIGHUP, sig_handler) == SIG_ERR) { printf("Fail to register signal handler\n"); return 1; } bufs = malloc(sizeof(void *) * buf_count); if (!bufs) return 1; memset(bufs, 0, sizeof(void *) * buf_count); srandom(pid); while (1) { int madvise_free = madvise_free = random() % 2; alloc_bufs(bufs, buf_count, buf_size); fill_bufs(bufs, buf_count, buf_size); /* We touched buffers so MADV_FREE cannot free pages */ check_madvise_bufs(bufs, buf_count, buf_size, 0); madvise_bufs(bufs, buf_count, buf_size, advise); sleep(1); /* syscall MADV_FREE */ madvise_free_bufs(bufs, buf_count, buf_size); sleep(1); check_madvise_bufs(bufs, buf_count, buf_size, 1); free_bufs(bufs, buf_count, buf_size); } return 0; }
Attachment:
oops.sh
Description: Bourne shell script
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setup_memcg.sh
Description: Bourne shell script