Messages in this thread | | | From | "H. Peter Anvin" <> | Subject | Re: [PATCH] 1-2-3 GB | Date | 13 Jan 2002 12:24:03 -0800 |
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Followup to: <Pine.LNX.4.21.0201121825200.1105-100000@localhost.localdomain> By author: Hugh Dickins <hugh@veritas.com> In newsgroup: linux.dev.kernel > > Usually not a problem: but if you configure for 1GB of user virtual > and 3GB of kernel virtual, and you have more than 1GB of physical > memory (as you normally would if chose HIGHMEM64G), then there's > a page at physical address 0x3ffff000, directly mapped to virtual > address 0x7ffff000. And if that page happens to get used for the > pmd of a process, then on exit the free_one_pgd loop wraps over > to carry on freeing "entries" at 0x80000000, 0x80000008, ... > A lot of pmd_ERROR messages, but eventually an entry scrapes > through the pmd_bad test and is wrongly freed, not so good. >
By the way, expect user programs to fail due to lack of address space if you only give them 1 GB of userspace. At 1 GB of userspace there is *no* address space which is compatible with the normal address space map available to the user process.
I would personally vote against including that particular option.
-hpa -- <hpa@transmeta.com> at work, <hpa@zytor.com> in private! "Unix gives you enough rope to shoot yourself in the foot." http://www.zytor.com/~hpa/puzzle.txt <amsp@zytor.com> - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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