Date: Sun, 16 Apr 2023 21:05:49 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 270810] munmap does not always sync the underlying file Message-ID: <bug-270810-227-q6eGVeB6JE@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-270810-227@https.bugs.freebsd.org/bugzilla/> References: <bug-270810-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D270810 --- Comment #6 from geoffrey@dommett.com --- The smallest test program that I have replicated this with is below. When run on a linux machine the problem does not occur, when writing to the= nfs server running bsd. When run on a bsd machine, the problem seems to occur if the number of instances run is sufficient that the machine has insufficient ram that it m= ust page between the files and the in memory copy to complete the operation. Wh= en running 50 instances is enough on the machine in front of me with 8gb of ram about 30% of them are corrupt at the end. It does not occur running just a = few instances.=20 Running 50 instances of this test on a bsd machine with 96Gb ram, 1 of them= is corrupt. This same machine exhibits a lot of corruption when 300+ Gb of fil= es are mapped. I think all times I have encountered this have been when the total files ma= pped exceed the physical ram of the machine. leaving in or commenting out the msync, fsync and ftruncate at the end does= not stop the file corruption.=20 #include <stdio.h> #include <sys/mman.h> #include <sys/stat.h> #include <sys/types.h> #include <fcntl.h> #include <unistd.h> int main (int argv , char** argc ) { int fl=3Dopen(argc[1] , O_RDWR | O_CREAT , 0644 ) ; lseek(fl,1000000000 , SEEK_SET); write(fl, "", 1); int * ttv =3D (int*) mmap(0,100000000 , PROT_WRITE | PROT_READ ,MAP_SHARED= , fl , 0) ; for (int j=3D0 ; j<10 ; j++) { for (int ii =3D j ; ii<100000000/4 ; ii+=3D10 ) ttv[ii]=3Dii ; } //msync(ttv , 10000000000, MS_SYNC ) ; //fsync(fl) ; //ftruncate(fl ,9000000000) ; close(fl) ; } --=20 You are receiving this mail because: You are the assignee for the bug.=
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