On 2023/02/15 15:35, lijiang wrote:>>> Hi, Kazu >>> Thank you for the comment. >>> >>> On Wed, Feb 15, 2023 at 1:38 PM HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab@xxxxxxx <mailto:k-hagio-ab@xxxxxxx>> wrote: >>> >>> On 2023/02/14 23:37, Lianbo Jiang wrote: >>> > The "kmem -i" option may output the bogus statistics of CACHED, which >>> > might be observed when some extreme situations occur in kernel, such as >>> > OOM, disk IO errors, etc. >>> > >>> > The following result of calculation may be a negative value, refer to >>> > the dump_kmeminfo(): >>> > page_cache_size = nr_file_pages - swapper_space_nrpages - buffer_pages; >>> > >>> > As a result, the negative value will be converted to unsigned long >>> > integer, eventually it overflows and gets a big integer. >>> > >>> > crash> kmem -i >>> > PAGES TOTAL PERCENTAGE >>> > TOTAL MEM 255314511 973.9 GB ---- >>> > FREE 533574 2 GB 0% of TOTAL MEM >>> > USED 254780937 971.9 GB 99% of TOTAL MEM >>> > SHARED 1713 6.7 MB 0% of TOTAL MEM >>> > BUFFERS 374 1.5 MB 0% of TOTAL MEM >>> > CACHED -114 70368744177664 GB 72251060080% of TOTAL MEM >>> > ^^^^ ^^^^^^^^^^^^^^ ^^^^^^^^^^^^ >>> >>> I think that this is not very bad output :) because we can notice >>> the negative value. Maybe it's due to future kernel changes. >>> >>> >>> It's true. But it is also easy to mislead users, because it is not clear whether the crash tool >>> gave a wrong result. >>> >>> Actually this issue was observed on the kernel 3.10. >>> >>> So if you set it to zero, what about emitting an info message? >>> >>> >>> It should be good to have an info message. >>> >>> + if (page_cache_size < 0) { >>> + error(INFO, "page_cache_size went negative (%ld), setting to 0\n", >>> + page_cache_size); >>> + page_cache_size = 0; >>> + } >>> >>> >>> Looks good. ok thanks for checking, applied. https://github.com/crash-utility/crash/commit/277da34dd5da8c1280d0d0fd7ce50499b31c3a58 Thanks, Kazu -- Crash-utility mailing list Crash-utility@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/crash-utility Contribution Guidelines: https://github.com/crash-utility/crash/wiki
