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2017-09-13mm: treewide: remove GFP_TEMPORARY allocation flagMichal Hocko
GFP_TEMPORARY was introduced by commit e12ba74d8ff3 ("Group short-lived and reclaimable kernel allocations") along with __GFP_RECLAIMABLE. It's primary motivation was to allow users to tell that an allocation is short lived and so the allocator can try to place such allocations close together and prevent long term fragmentation. As much as this sounds like a reasonable semantic it becomes much less clear when to use the highlevel GFP_TEMPORARY allocation flag. How long is temporary? Can the context holding that memory sleep? Can it take locks? It seems there is no good answer for those questions. The current implementation of GFP_TEMPORARY is basically GFP_KERNEL | __GFP_RECLAIMABLE which in itself is tricky because basically none of the existing caller provide a way to reclaim the allocated memory. So this is rather misleading and hard to evaluate for any benefits. I have checked some random users and none of them has added the flag with a specific justification. I suspect most of them just copied from other existing users and others just thought it might be a good idea to use without any measuring. This suggests that GFP_TEMPORARY just motivates for cargo cult usage without any reasoning. I believe that our gfp flags are quite complex already and especially those with highlevel semantic should be clearly defined to prevent from confusion and abuse. Therefore I propose dropping GFP_TEMPORARY and replace all existing users to simply use GFP_KERNEL. Please note that SLAB users with shrinkers will still get __GFP_RECLAIMABLE heuristic and so they will be placed properly for memory fragmentation prevention. I can see reasons we might want some gfp flag to reflect shorterm allocations but I propose starting from a clear semantic definition and only then add users with proper justification. This was been brought up before LSF this year by Matthew [1] and it turned out that GFP_TEMPORARY really doesn't have a clear semantic. It seems to be a heuristic without any measured advantage for most (if not all) its current users. The follow up discussion has revealed that opinions on what might be temporary allocation differ a lot between developers. So rather than trying to tweak existing users into a semantic which they haven't expected I propose to simply remove the flag and start from scratch if we really need a semantic for short term allocations. [1] http://lkml.kernel.org/r/20170118054945.GD18349@bombadil.infradead.org [akpm@linux-foundation.org: fix typo] [akpm@linux-foundation.org: coding-style fixes] [sfr@canb.auug.org.au: drm/i915: fix up] Link: http://lkml.kernel.org/r/20170816144703.378d4f4d@canb.auug.org.au Link: http://lkml.kernel.org/r/20170728091904.14627-1-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Matthew Wilcox <willy@infradead.org> Cc: Neil Brown <neilb@suse.de> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-21string_helpers: add kstrdup_quotable_fileKees Cook
Allocate a NULL-terminated file path with special characters escaped, safe for logging. Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: James Morris <james.l.morris@oracle.com>
2016-04-21string_helpers: add kstrdup_quotable_cmdlineKees Cook
Provide an escaped (but readable: no inter-argument NULLs) commandline safe for logging. Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: James Morris <james.l.morris@oracle.com>
2016-04-21string_helpers: add kstrdup_quotableKees Cook
Handle allocating and escaping a string safe for logging. Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: James Morris <james.l.morris@oracle.com>
2016-01-20string_helpers: fix precision loss for some inputsJames Bottomley
It was noticed that we lose precision in the final calculation for some inputs. The most egregious example is size=3000 blk_size=1900 in units of 10 should yield 5.70 MB but in fact yields 3.00 MB (oops). This is because the current algorithm doesn't correctly account for all the remainders in the logarithms. Fix this by doing a correct calculation in the remainders based on napier's algorithm. Additionally, now we have the correct result, we have to account for arithmetic rounding because we're printing 3 digits of precision. This means that if the fourth digit is five or greater, we have to round up, so add a section to ensure correct rounding. Finally account for all possible inputs correctly, including zero for block size. Fixes: b9f28d863594c429e1df35a0474d2663ca28b307 Signed-off-by: James Bottomley <JBottomley@Odin.com> Reported-by: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: <stable@vger.kernel.org> [delay until after 4.4 release] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-17lib/string_helpers.c: fix infinite loop in string_get_size()Vitaly Kuznetsov
Some string_get_size() calls (e.g.: string_get_size(1, 512, STRING_UNITS_10, ..., ...) string_get_size(15, 64, STRING_UNITS_10, ..., ...) ) result in an infinite loop. The problem is that if size is equal to divisor[units]/blk_size and is smaller than divisor[units] we'll end up with size == 0 when we start doing sf_cap calculations: For string_get_size(1, 512, STRING_UNITS_10, ..., ...) case: ... remainder = do_div(size, divisor[units]); -> size is 0, remainder is 1 remainder *= blk_size; -> remainder is 512 ... size *= blk_size; -> size is still 0 size += remainder / divisor[units]; -> size is still 0 The caller causing the issue is sd_read_capacity(), the problem was noticed on Hyper-V, such weird size was reported by host when scanning collides with device removal. This is probably a separate issue worth fixing, this patch is intended to prevent the library routine from infinite looping. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Acked-by: James Bottomley <JBottomley@Odin.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: "K. Y. Srinivasan" <kys@microsoft.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-10lib/string_helpers: rename "esc" arg to "only"Kees Cook
To further clarify the purpose of the "esc" argument, rename it to "only" to reflect that it is a limit, not a list of additional characters to escape. Signed-off-by: Kees Cook <keescook@chromium.org> Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-10lib/string_helpers: clarify esc arg in string_escape_memKees Cook
The esc argument is used to reduce which characters will be escaped. For example, using " " with ESCAPE_SPACE will not produce any escaped spaces. Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Mathias Krause <minipli@googlemail.com> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-16Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsiLinus Torvalds
Pull SCSI updates from James Bottomley: "This is the usual grab bag of driver updates (lpfc, qla2xxx, storvsc, aacraid, ipr) plus an assortment of minor updates. There's also a major update to aic1542 which moves the driver into this millenium" * tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (106 commits) change SCSI Maintainer email sd, mmc, virtio_blk, string_helpers: fix block size units ufs: add support to allow non standard behaviours (quirks) ufs-qcom: save controller revision info in internal structure qla2xxx: Update driver version to 8.07.00.18-k qla2xxx: Restore physical port WWPN only, when port down detected for FA-WWPN port. qla2xxx: Fix virtual port configuration, when switch port is disabled/enabled. qla2xxx: Prevent multiple firmware dump collection for ISP27XX. qla2xxx: Disable Interrupt handshake for ISP27XX. qla2xxx: Add debugging info for MBX timeout. qla2xxx: Add serdes read/write support for ISP27XX qla2xxx: Add udev notification to save fw dump for ISP27XX qla2xxx: Add message for sucessful FW dump collected for ISP27XX. qla2xxx: Add support to load firmware from file for ISP 26XX/27XX. qla2xxx: Fix beacon blink for ISP27XX. qla2xxx: Increase the wait time for firmware to be ready for P3P. qla2xxx: Fix crash due to wrong casting of reg for ISP27XX. qla2xxx: Fix warnings reported by static checker. lpfc: Update version to 10.5.0.0 for upstream patch set lpfc: Update copyright to 2015 ...
2015-04-15lib/string_helpers.c: change semantics of string_escape_memRasmus Villemoes
The current semantics of string_escape_mem are inadequate for one of its current users, vsnprintf(). If that is to honour its contract, it must know how much space would be needed for the entire escaped buffer, and string_escape_mem provides no way of obtaining that (short of allocating a large enough buffer (~4 times input string) to let it play with, and that's definitely a big no-no inside vsnprintf). So change the semantics for string_escape_mem to be more snprintf-like: Return the size of the output that would be generated if the destination buffer was big enough, but of course still only write to the part of dst it is allowed to, and (contrary to snprintf) don't do '\0'-termination. It is then up to the caller to detect whether output was truncated and to append a '\0' if desired. Also, we must output partial escape sequences, otherwise a call such as snprintf(buf, 3, "%1pE", "\123") would cause printf to write a \0 to buf[2] but leaving buf[0] and buf[1] with whatever they previously contained. This also fixes a bug in the escaped_string() helper function, which used to unconditionally pass a length of "end-buf" to string_escape_mem(); since the latter doesn't check osz for being insanely large, it would happily write to dst. For example, kasprintf(GFP_KERNEL, "something and then %pE", ...); is an easy way to trigger an oops. In test-string_helpers.c, the -ENOMEM test is replaced with testing for getting the expected return value even if the buffer is too small. We also ensure that nothing is written (by relying on a NULL pointer deref) if the output size is 0 by passing NULL - this has to work for kasprintf("%pE") to work. In net/sunrpc/cache.c, I think qword_add still has the same semantics. Someone should definitely double-check this. In fs/proc/array.c, I made the minimum possible change, but longer-term it should stop poking around in seq_file internals. [andriy.shevchenko@linux.intel.com: simplify qword_add] [andriy.shevchenko@linux.intel.com: add missed curly braces] Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-15lib/string_helpers.c: refactor string_escape_memRasmus Villemoes
When printf is given the format specifier %pE, it needs a way of obtaining the total output size that would be generated if the buffer was large enough, and string_escape_mem doesn't easily provide that. This is a refactorization of string_escape_mem in preparation of changing its external API to provide that information. The somewhat ugly early returns and subsequent seemingly redundant conditionals are to make the following patch touch as little as possible in string_helpers.c while still preserving the current behaviour of never outputting partial escape sequences. That behaviour must also change for %pE to work as one expects from every other printf specifier. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-10sd, mmc, virtio_blk, string_helpers: fix block size unitsJames Bottomley
The current string_get_size() overflows when the device size goes over 2^64 bytes because the string helper routine computes the suffix from the size in bytes. However, the entirety of Linux thinks in terms of blocks, not bytes, so this will artificially induce an overflow on very large devices. Fix this by making the function string_get_size() take blocks and the block size instead of bytes. This should allow us to keep working until the current SCSI standard overflows. Also fix virtio_blk and mmc (both of which were also artificially multiplying by the block size to pass a byte side to string_get_size()). The mathematics of this is pretty simple: we're taking a product of size in blocks (S) and block size (B) and trying to re-express this in exponential form: S*B = R*N^E (where N, the exponent is either 1000 or 1024) and R < N. Mathematically, S = RS*N^ES and B=RB*N^EB, so if RS*RB < N it's easy to see that S*B = RS*RB*N^(ES+EB). However, if RS*BS > N, we can see that this can be re-expressed as RS*BS = R*N (where R = RS*BS/N < N) so the whole exponent becomes R*N^(ES+EB+1) [jejb: fix incorrect 32 bit do_div spotted by kbuild test robot <fengguang.wu@intel.com>] Acked-by: Ulf Hansson <ulf.hansson@linaro.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: James Bottomley <JBottomley@Odin.com>
2015-02-12libstring_helpers.c:string_get_size(): return voidRasmus Villemoes
string_get_size() was documented to return an error, but in fact always returned 0. Since the output always fits in 9 bytes, just document that and let callers do what they do now: pass a small stack buffer and ignore the return value. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12lib/string_helpers.c:string_get_size(): use 32 bit arithmetic when possibleRasmus Villemoes
The remainder from do_div is always a u32, and after size has been reduced to be below 1000 (or 1024), it certainly fits in u32. So both remainder and sf_cap can be made u32s, the format specifiers can be simplified (%lld wasn't the right thing to use for _unsigned_ long long anyway), and we can replace a do_div with an ordinary 32/32 bit division. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12lib/string_helpers.c:string_get_size(): remove redundant prefixesRasmus Villemoes
While commit 3c9f3681d0b4 ("[SCSI] lib: add generic helper to print sizes rounded to the correct SI range") says that Z and Y are included in preparation for 128 bit computers, they just waste .text currently. If and when we get u128, string_get_size needs updating anyway (and ISO needs to come up with four more prefixes). Also there's no need to include and test for the NULL sentinel; once we reach "E" size is at most 18. [The test is also wrong; it should be units_str[units][i+1]; if we've reached NULL we're already doomed.] Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-14lib / string_helpers: introduce string_escape_mem()Andy Shevchenko
This is almost the opposite function to string_unescape(). Nevertheless it handles \0 and could be used for any byte buffer. The documentation is supplied together with the function prototype. The test cases covers most of the scenarios and would be expanded later on. [akpm@linux-foundation.org: avoid 1k stack consumption] Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: "John W . Linville" <linville@tuxdriver.com> Cc: Johannes Berg <johannes@sipsolutions.net> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Joe Perches <joe@perches.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-14lib / string_helpers: move documentation to c-fileAndy Shevchenko
The introduced function string_escape_mem() is a kind of opposite to string_unescape. We have several users of such functionality each of them created custom implementation. The series contains clean up of test suite, adding new call, and switching few users to use it via %*pE specifier. Test suite covers all of existing and most of potential use cases. This patch (of 11): The documentation of API belongs to c-file. This patch moves it accordingly. There is no functional change. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: "John W . Linville" <linville@tuxdriver.com> Cc: Johannes Berg <johannes@sipsolutions.net> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-08-06lib/string_helpers.c: constify static arraysMathias Krause
Complement commit 68aecfb97978 ("lib/string_helpers.c: make arrays static") by making the arrays const -- not only pointing to const strings. This moves them out of the data section to the r/o data section: text data bss dec hex filename 1150 176 0 1326 52e lib/string_helpers.old.o 1326 0 0 1326 52e lib/string_helpers.new.o Signed-off-by: Mathias Krause <minipli@googlemail.com> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-30lib/string_helpers: introduce generic string_unescapeAndy Shevchenko
There are several places in kernel where modules unescapes input to convert C-Style Escape Sequences into byte codes. The patch provides generic implementation of such approach. Test cases are also included into the patch. [akpm@linux-foundation.org: clarify comment] [akpm@linux-foundation.org: export get_random_int() to modules] Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Samuel Thibault <samuel.thibault@ens-lyon.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jason Baron <jbaron@redhat.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: William Hubbs <w.d.hubbs@gmail.com> Cc: Chris Brannon <chris@the-brannons.com> Cc: Kirk Reiser <kirk@braille.uwo.ca> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29lib/string_helpers.c: make arrays staticAndrew Morton
Moving these arrays into static storage shrinks the kernel a bit: text data bss dec hex filename 723 112 64 899 383 lib/string_helpers.o 516 272 64 852 354 lib/string_helpers.o Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-07lib: reduce the use of module.h wherever possiblePaul Gortmaker
For files only using THIS_MODULE and/or EXPORT_SYMBOL, map them onto including export.h -- or if the file isn't even using those, then just delete the include. Fix up any implicit include dependencies that were being masked by module.h along the way. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2008-10-23[SCSI] lib: string_get_size(): don't hang on zero; no decimals on exactH. Peter Anvin
We would hang forever when passing a zero to string_get_size(). Furthermore, string_get_size() would produce decimals on a value small enough to be exact. Finally, a few formatting issues are inconsistent with standard SI style guidelines. - If the value is less than the divisor, skip the entire rounding step. This prints out all small values including zero as integers, without decimals. - Add a space between the value and the symbol for the unit, consistent with standard SI practice. - Lower case k in kB since we are talking about powers of 10. - Finally, change "int" to "unsigned int" in one place to shut up a gcc warning when compiling the code out-of-kernel for testing. Signed-off-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-10-03[SCSI] lib: add generic helper to print sizes rounded to the correct SI rangeJames Bottomley
This patch adds the ability to print sizes in either units of 10^3 (SI) or 2^10 (Binary) units. It rounds up to three significant figures and can be used for either memory or storage capacities. Oh, and I'm fully aware that 64 bits is only 16EiB ... the Zetta and Yotta units are added for future proofing against the day we have 128 bit computers ... [fujita.tomonori@lab.ntt.co.jp: fix missed unsigned long long cast] Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>