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From: "nmiell at comcast dot net" <sourceware-bugzilla@sourceware.org> To: glibc-bugs@sources.redhat.com Subject: [Bug libc/3458] New: posix_madvise(addr, len, POSIX_MADV_DONTNEED) discards data Date: Sat, 04 Nov 2006 10:29:00 -0000 [thread overview] Message-ID: <20061104102854.3458.nmiell@comcast.net> (raw) POSIX describes the POSIX_MADV_DONTNEED parameter to posix_madvise as follows: POSIX_MADV_DONTNEED Specifies that the application expects that it will not access the specified range in the near future. Linux describes and implements the MADV_DONTNEED parameter to madvise as follows: MADV_DONTNEED Do not expect access in the near future. (For the time being, the application is finished with the given range, so the kernel can free resources associated with it.) Subsequent accesses of pages in this range will succeed, but will result either in re-loading of the memory contents from the underlying mapped file (see mmap()) or zero-fill-on-demand pages for mappings without an underlying file. glibc transparently forwards calls to posix_madvise to madvise, which means that POSIX conformant applications which use posix_madvise(addr, len, POSIX_MADV_DONTNEED) will corrupt data. Suggested fix: Implement posix_madvise as a small wrapper around madvise which silently discards all calls using POSIX_MADV_DONTNEED, fails for values other than POSIX_MADV_*, and forwards the remainder. -- Summary: posix_madvise(addr, len, POSIX_MADV_DONTNEED) discards data Product: glibc Version: unspecified Status: NEW Severity: normal Priority: P2 Component: libc AssignedTo: drepper at redhat dot com ReportedBy: nmiell at comcast dot net CC: glibc-bugs at sources dot redhat dot com http://sourceware.org/bugzilla/show_bug.cgi?id=3458 ------- You are receiving this mail because: ------- You are on the CC list for the bug, or are watching someone who is.
next reply other threads:[~2006-11-04 10:29 UTC|newest] Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top 2006-11-04 10:29 nmiell at comcast dot net [this message] 2006-11-05 5:45 ` [Bug libc/3458] " nmiell at comcast dot net 2007-02-17 9:07 ` drepper at redhat dot com 2007-02-17 20:35 ` nmiell at comcast dot net 2007-02-18 13:56 ` aj at suse dot de 2007-02-21 19:04 ` drepper at redhat dot com 2007-03-01 18:13 ` samuel dot thibault at ens-lyon dot org 2007-03-01 18:15 ` samuel dot thibault at ens-lyon dot org 2007-07-12 14:57 ` cvs-commit at gcc dot gnu dot org
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