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Fri, 13 Sep 2019 12:29:10 -0700 Received: by devbig059.prn3.facebook.com (Postfix, from userid 4924) id C9B33174196F; Fri, 13 Sep 2019 12:29:09 -0700 (PDT) Smtp-Origin-Hostprefix: devbig From: Lucian Adrian Grijincu Smtp-Origin-Hostname: devbig059.prn3.facebook.com To: Lucian Adrian Grijincu , , Souptick Joarder CC: , Michal Hocko , Andrew Morton , Rik van Riel , Roman Gushchin Smtp-Origin-Cluster: prn3c05 Subject: [PATCH] mm: memory: fix /proc/meminfo reporting for MLOCK_ONFAULT Date: Fri, 13 Sep 2019 12:29:07 -0700 Message-ID: <20190913192907.96530-1-lucian@fb.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: References: X-FB-Internal: Safe MIME-Version: 1.0 Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.70,1.0.8 definitions=2019-09-13_09:2019-09-11,2019-09-13 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 phishscore=0 lowpriorityscore=0 adultscore=0 clxscore=1015 mlxlogscore=716 spamscore=0 bulkscore=0 malwarescore=0 suspectscore=2 priorityscore=1501 impostorscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1908290000 definitions=main-1909130199 X-FB-Internal: deliver X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: As pages are faulted in MLOCK_ONFAULT correctly updates /proc/self/smaps, but doesn't update /proc/meminfo's Mlocked field. - Before this /proc/meminfo fields didn't change as pages were faulted in: ``` = Start = /proc/meminfo Unevictable: 10128 kB Mlocked: 10132 kB = Creating testfile = = after mlock2(MLOCK_ONFAULT) = /proc/meminfo Unevictable: 10128 kB Mlocked: 10132 kB /proc/self/smaps 7f8714000000-7f8754000000 rw-s 00000000 08:04 50857050 /root/testfile Locked: 0 kB = after reading half of the file = /proc/meminfo Unevictable: 10128 kB Mlocked: 10132 kB /proc/self/smaps 7f8714000000-7f8754000000 rw-s 00000000 08:04 50857050 /root/testfile Locked: 524288 kB = after reading the entire the file = /proc/meminfo Unevictable: 10128 kB Mlocked: 10132 kB /proc/self/smaps 7f8714000000-7f8754000000 rw-s 00000000 08:04 50857050 /root/testfile Locked: 1048576 kB = after munmap = /proc/meminfo Unevictable: 10128 kB Mlocked: 10132 kB /proc/self/smaps ``` - After: /proc/meminfo fields are properly updated as pages are touched: ``` = Start = /proc/meminfo Unevictable: 60 kB Mlocked: 60 kB = Creating testfile = = after mlock2(MLOCK_ONFAULT) = /proc/meminfo Unevictable: 60 kB Mlocked: 60 kB /proc/self/smaps 7f2b9c600000-7f2bdc600000 rw-s 00000000 08:04 63045798 /root/testfile Locked: 0 kB = after reading half of the file = /proc/meminfo Unevictable: 524220 kB Mlocked: 524220 kB /proc/self/smaps 7f2b9c600000-7f2bdc600000 rw-s 00000000 08:04 63045798 /root/testfile Locked: 524288 kB = after reading the entire the file = /proc/meminfo Unevictable: 1048496 kB Mlocked: 1048508 kB /proc/self/smaps 7f2b9c600000-7f2bdc600000 rw-s 00000000 08:04 63045798 /root/testfile Locked: 1048576 kB = after munmap = /proc/meminfo Unevictable: 176 kB Mlocked: 60 kB /proc/self/smaps ``` Repro code. --- int mlock2wrap(const void* addr, size_t len, int flags) { return syscall(SYS_mlock2, addr, len, flags); } void smaps() { char smapscmd[1000]; snprintf( smapscmd, sizeof(smapscmd) - 1, "grep testfile -A 20 /proc/%d/smaps | grep -E '(testfile|Locked)'", getpid()); printf("/proc/self/smaps\n"); fflush(stdout); system(smapscmd); } void meminfo() { const char* meminfocmd = "grep -E '(Mlocked|Unevictable)' /proc/meminfo"; printf("/proc/meminfo\n"); fflush(stdout); system(meminfocmd); } { \ int rc = (call); \ if (rc != 0) { \ printf("error %d %s\n", rc, strerror(errno)); \ exit(1); \ } \ } int main(int argc, char* argv[]) { printf("= Start =\n"); meminfo(); printf("= Creating testfile =\n"); size_t size = 1 << 30; // 1 GiB int fd = open("testfile", O_CREAT | O_RDWR, 0666); { void* buf = malloc(size); write(fd, buf, size); free(buf); } int ret = 0; void* addr = NULL; addr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); if (argc > 1) { PCHECK(mlock2wrap(addr, size, MLOCK_ONFAULT)); printf("= after mlock2(MLOCK_ONFAULT) =\n"); meminfo(); smaps(); for (size_t i = 0; i < size / 2; i += 4096) { ret += ((char*)addr)[i]; } printf("= after reading half of the file =\n"); meminfo(); smaps(); for (size_t i = 0; i < size; i += 4096) { ret += ((char*)addr)[i]; } printf("= after reading the entire the file =\n"); meminfo(); smaps(); } else { PCHECK(mlock(addr, size)); printf("= after mlock =\n"); meminfo(); smaps(); } PCHECK(munmap(addr, size)); printf("= after munmap =\n"); meminfo(); smaps(); return ret; } --- Signed-off-by: Lucian Adrian Grijincu --- mm/memory.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/memory.c b/mm/memory.c index e0c232fe81d9..55da24f33bc4 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3311,6 +3311,8 @@ vm_fault_t alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg, } else { inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page)); page_add_file_rmap(page, false); + if (vma->vm_flags & VM_LOCKED && !PageTransCompound(page)) + mlock_vma_page(page); } set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry); -- 2.17.1